Theology: The Definitive Guide to Getting Started

What is theology?

At its core, theology (as mentioned above) is “the study of God.” The etymology of theology means literally “speech of God” (theo, “God”; logia, “words,” “discourse”). Theology is the discipline of learning how to speak of God in a way most proper to the divine nature—at least, the best we can manage. For many church fathers, for example, poor theology is speaking of God or attributing to God what is “unworthy of God.” For example, the misconception that God has literal fingers and toes is a result of thinking of God as a human, not as God. Our patterns of thought tend to anthropomorphize, and this can obscure God’s true nature if we aren’t careful, and even cause us to speak falsely of him. Thus attributing human attributes to God, who is bodiless, is a failure to speak of God in a manner worthy of God. This makes theology the ultimate challenge for the human mind, for it requires us to disrupt and revise our normal categories and habits of thought.

For Christians, theology is inextricably associated with Scripture, for the words of Scripture are for us the best and most accurate expression of God. Non-Christians (Plato, for instance) can practice theology without Scripture, but Christian theology proper is inevitably biblical theology—that is, biblical theology is the foundation for all other theologies deserving the name “Christian.”

In his Systematic Theology: An Introduction to Christian Belief, evangelical theologian John Frame suggests a definition of theology along these lines: “Theology is the application of Scripture, by persons, to every area of life.”

Theology must be biblical, and its purpose is deeply tied to the church, to the actual lives of real Christians. We shouldn’t involve ourselves in theology simply to understand biblical principles and debate doctrines. Theology changes how we see the world and how we live. James tells us to be doers of the word, not just hearers (1:22). When we keep the local church and its needs in mind as we study and communicate theology, we help the Christian body to develop in Christlikeness and fulfill its Great Commission responsibilities.

Table of contents

Feel free to read this page straight through or skip down to the sections most interesting to you:

• Types of theology
• Key theologians
• Key theological questions
• Resources to help you study theology
• 4 steps to developing theological convictions
• Conclusion

Types of theology

In Dictionary of Theological Terms, Alan Cairns defines natural theology as, “The science which on the principles of human reason and conscience, considering the evidences of God’s works in creation and providence, seeks to construct a scientific knowledge of God—i.e., it seeks to ascertain (1) Is there a God? (2) What is his nature? (3) In what relation does he stand to man?” Natural theology includes all the ways we can know about God outside his specific revelation through the Bible.

Paul describes this in Romans 1:20: “For his invisible attributes, that is, his eternal power and divine nature, have been clearly seen since the creation of the world, being understood through what he has made. As a result, people are without excuse” (CSB).

While most theologians have accepted that certain truths about God’s existence, power, and character can be obtained through natural theology (as the psalmist tells us in 19:1: “The heavens declare the glory of God, and the expanse proclaims the work of his hands”), most theologians have also understood there are limitations to this approach. Certain others truth of God, such as the fact that he is triune, remain inaccessible through natural theology, but require a special revelation on God’s part.

Not only is nature limited in what it can tell us about God, but the human intellect is often too frail to comprehend or rightly interpret what theology nature can tell. For example, according to the Pocket Dictionary of the Reformed Tradition, John Calvin believed that “humans have an awareness of God (sensus divinitatis) and encounter some of his attributes in nature, but sinful minds inevitably distort this awareness and prevent saving knowledge.”

Historical theology represents the marriage of theology and church history. The discipline focuses on the development of theological doctrines throughout more than two thousand years of church history.

A. C. Thiselton writes in the Thiselton Companion to Christian Theology: “Theology is never purely abstract. It answers questions that arise from a series of specific contexts and events.” Historical theology doesn’t focus on the people or the events of church history but the ideas that sprung from these events and how they developed over time.

While the development of these historical doctrines of the Christian church never trumps biblical revelation, they do ensure we’re interpreting Scripture within the bounds of orthodoxy. We recognize that we study the Bible and live out its principles surrounded by a “great cloud of witnesses” (Heb 12:1) and that we aren’t the only ones whom Christ’s Spirit guides “into all truth” (John 16:13).

Historical theology is often divided into subsets depending upon the era. Anglican theologian Alister McGrath describes four such eras in his book Historical Theology: the Patristic, Medieval, Reformation, and Modern. All major doctrines of the Christian faith show development and refinement throughout these four eras.

The systematic approach studies the entire scope of the Bible by looking at everything Scripture teaches about a particular topic or issue and describes the biblical and historical development of the theological doctrines. According to the Lexham Bible Dictionary, it’s “an approach to the Bible that seeks to draw biblical teachings and themes into a self-consistent, coherent whole, in conversation with the history of Christian theological reflection and contemporary issues confronting the church.”

Because of the frequent dependence upon systematic theology to develop Christian creeds and doctrinal statements, it’s a popular approach to theology that has led to some of the most significant theological works in church history, including Thomas Aquinas’ Summa Theologica, Herman Bavinck’s Reformed Dogmatics, John Calvin’s Institutes of Christian Religion, and Karl Barth’s Church Dogmatics.

At times, systematic theologians have needed to defend their discipline from other theologians who accuse them of bending Scripture to squeeze doctrine into artificial theological systems. At its best, though, systematic theologians help the church to speak authoritatively and biblically on specific topics of consequence.

As described in the Holman Illustrated Bible Dictionary, biblical theology is the “discussion of what the Bible itself teaches about God and his dealings with human beings and the rest of creation.” Biblical theology provides the foundation for natural, systematic, and historical theology because it represents the exegetical work required for all theological study.

Although believers have developed biblical theology for as long as the Bible has existed, it became a separate field of study in the eighteenth century in reaction against dogmatic (or systematic) theology. The Oxford Dictionary of the Christian Church defines five typical characteristics of biblical theology:

1. Biblical concepts take preference over all others.
2. Biblical concepts are sufficient for all “essential purposes.”
3. God’s work in history is the primary medium of revelation.
4. It emphasizes the “inner coherence of the biblical material.”
5. It tends toward a conservative attitude about the historical integrity of Scripture.

In the church of Jesus Christ, there can and should be no non-theologians.
—Karl Barth

While many theologians through the ages have impacted the development of the church’s doctrinal teachings, certain figures have played an outsized role. It’s hard to narrow the most influential theologians to a list of three. Most theologians exert influence over a single theological tradition or denomination. Others have impacted all (or most of) the church. The following list is not exhaustive, but it names some of the pivotal players to help you get started.

Paul

It’s impossible to overstate the impact of the apostle Paul on the theological development of the church. Not only did he write most of the New Testament, but his letters have been the doctrinal center of the major theological works of the past two thousand years. Not only did Paul do theology, but in the early church he was considered the model theologian for all other theologians.

Born Saul of Tarsus (on the southern coast of modern-day Turkey), Paul learned Judaism under the teaching of the influential Jewish leader Gamaliel. The passionate persecutor of the early church converted to Christianity after encountering a risen Jesus on the road to Damascus as described in Acts 9. He became one of the most proficient missionaries in church history, traveling throughout the known world to share the gospel. His letters to the churches he started became the basis for much of the New Testament. Although the letters were written to address specific issues within the churches, the principles he taught have shaped the church’s teachings on numerous topics. 

The Lexham Bible Dictionary describes the book of Romans as the “text that best resembles a fully voiced theological manifesto.” It’s also likely his most controversial letter. In it, Paul addresses his theological views on salvation, faith, sin and judgment, the law, and more. 

Origen of Alexandria

Origen has a mixed reception in Christian history, to understate the matter. Though teachings attached to his name would be condemned as heresy after his death, there’s no denying Origen has profoundly influenced Christianity. Many great theologians of the church, including Athanasius of Alexandria, Gregory of Nyssa, and Ambrose of Milan (the mentor of Augustine) express their respect and gratitude for his teachings. In this respect, it is understandable why Origen provokes so much controversy: he is precisely the sort of figure we cannot ignore, whether we like him or not.

Origen was one of the most prolific authors of the ancient world, but his most famous work is On First Principles. This is a preparatory text for pastoral exegesis, but it has also been called the church’s very first systematic theology. There he articulates the doctrine of the eternal generation of the Son from the Father, which would be indispensable for the Nicene formulation of the Trinity. Origen boasts many other “firsts” for the church. For example, his recently discovered Homilies on the Psalms is the first exegetical treatment of that book by a Christian.

Athanasius of Alexandria

This fourth-century bishop of Alexandria attended the Nicene Council (325) and was among the authors and defenders of the Nicene Creed. His main antagonist was Arianism, a Christian heresy which denied that divinity of the Son of God by arguing that the Son was not co-eternal with the Father but was at some point created. Athanasius’s most famous book, On the Incarnation, is a true Christian classic as accessible as it is deep. In this work, Athanasius explores how the incarnation of the Son effects out salvation. The root thesis is anti-Arian: Athanasius demonstrates that if we are to be saved, our Savior and our Creator must be the same person.

For his anti-Arian views, Athanasius spent many years in exile with the monks of the Egyptian desert. There he met Antony the Great and the two became fast friends. Shortly after Antony died, Athanasius wrote The Life of Antony, which presented a model of Christian spiritual discipline based on the great monk’s life and teachings. This little work would become one of the most influential writings of the early and medieval periods. In fact, it would play a major part in the conversion of Augustine of Hippo.

Augustine of Hippo

The famed bishop of Hippo is the most influential patristic theologian in the Latin-speaking West. Born in North Africa to a pagan father and a devout Christian mother, Augustine’s early study was in rhetoric, a key way to advance in public administration, according to The Westminster Dictionary of Theologians. His early study led him to embrace Manichaeism—a dualistic religious system with elements of Gnosticism, Christianity, and paganism—but after a dramatic experience in the Garden of Milan AD 386, he converted to Christianity.

Augustine would exercise his intellectual and rhetorical skills to deal with the Donatist and Pelagian controversies. His major theological works include The City of God, On the Trinity, and On Christian Doctrine.

Augustine is the father of Augustinianism, which The Pocket Dictionary of Theological Terms defines as: “A system of thought [that] essentially starts with the complete sinfulness of humankind (depravity), which leaves humans unable to respond in faith toward God.” While Augustinianism significantly impacted the development of medieval theology, it also influenced many of the reformers of fifteenth- and sixteenth-century Europe (particularly Martin Luther and John Calvin).

Augustinian theology is often contrasted with Pelagianism, the teachings of Augustine’s contemporaneous rival who believed people were “capable of avoiding sin and choosing to live righteous lives even apart from God’s grace,” according to The Lexham Bible Dictionary. It’s a battle Augustine clearly won. Most of the Christian church considers Pelagianism heretical today.

Gregory of Nazianzus

Gregory was one of the Great Cappadocians, a set of four teachers of the church comprised of Gregory, his good friend Basil of Caesarea, Basil’s brother Gregory of Nyssa, and their sister Macrina the Younger. These four each made major contributions to orthodox theology, but since this article is about how to begin, you can’t do worse than Gregory of Nazianzus.

Widely considered one of the most educated and skilled theologians of the patristic era, Gregory was Archbishop of Constantinople in the fourth century. He is widely considered the most accomplished rhetorical stylist of the patristic age. He is best known for his Five Theological Orations—a work that earned him the title “the Theologian” in the Orthodox tradition. (A great honor: the only other Christian writer to share this title is the author of the Gospel of John!) This work remains a standard of Trinitarian theology and no theological education is complete without it.

Thomas Aquinas

Aquinas taught in the thirteenth century. Today, he is known as “The Angelic Doctor,” but in his own day his university students nicknamed him “The Dumb Ox” for his heavy size and slow, quiet manner of speaking. Unappreciated in his own time, Pope Leo XIII in 1879 proclaimed that Thomism was a “definitive exposition of Catholic doctrine.” The Roman Catholic Church would eventually require Catholic teachers of philosophy and religion to follow the methods of Aquinas in the Code of Canon Law (1917)—effectively establishing Thomism as the official philosophy of the Roman Catholic Church.

Two centuries before Aquinas began teaching, the writings of Aristotle had returned to the West and brought into question many aspects of the church’s teachings. A philosophical–theological method emerged predicated upon Aristotle’s ten categories. Though this method, referred to as Scholasticism, had many early practitioners such as Anselm of Canterbury (11th cent.), Aquinas’s Summa Theologica is considered the pinnacle of Scholasticism.

Martin Luther

Martin Luther may be the West’s most influential single person since New Testament times. Originally an Augustinian monk, Luther first adopted the theological belief of nominalism, which gives man a specific but limited role in his own justification. The Oxford Dictionary of the Christian Church says of Luther, “He came to believe that man is unable to respond to God without divine grace, and that man can be justified only through faith (per solam fidem), by the merits of Christ imputed to him: works or religious observance are irrelevant.” A life-altering encounter with the truth of Romans 1:17 and Paul’s treatise on the righteousness of God set Luther’s theology on a new track that would have monumental consequences for Christendom. In October 1517, Luther famously nailed ninety-five theses on indulgences on the door of the Wittenberg Church, which set him on a collision course against Pope Leo X and the sixteenth-century Roman Catholic Church. 

Over the next three decades, Luther’s doctrinal exposition (along with his collaborator Philip Melanchthon) not only rocked the Christian church but the entirety of the Western world. He is widely credited as the founder of what became the Protestant Reformation, forming the third major branch of Christianity (along with Roman Catholicism and Eastern Orthodoxy). Among Luther’s most important books (by Luther’s own appraisal) are The Bondage of the Will, his Catechism, and his commentaries on Galatians and John 14–16.

Luther’s theological legacy is often called Lutheranism. According to The Pocket Dictionary of the Reformed Tradition, “While Lutheranism holds to the solas of the Reformation (sola fide, sola gratia, sola scriptura, soli deo gloria, solus Christus), it historically differs from Calvinism in such areas as its view of the consubstantiation of Christ’s body and blood in the Lord’s Supper, the ubiquity of Christ’s humanity in opposition to extra calvinisticum, and the distinctive separation of law and gospel.” 
The New Dictionary of Theology describes soteriology (the theology of human salvation) and the authority of God’s Word as the most influential doctrines of Lutheran theology.

Although various theological streams within the church define their beliefs differently, most will agree on the boundaries of the eight to ten major doctrines of the Christian faith. Many of these topics are outlined in the great creeds of early Christianity. While there is significant agreement around these topics, orthodox Christians also have diverse responses to many of the questions below.

Revelation

All significant theological reflection begins with a clarity around how we come to know truth. Many of the great questions we have around God center around our view of revelation. Under this broad theological topic are questions that relate to how God communicates with humanity, including:

• How do we gain knowledge about God?
• What is truth and how can we know it?
• How does God reveal himself to humanity?
• What is the mode of biblical inspiration?
• How did God use humans in the process of creating biblical texts?
• How does God intend us to understand the Bible?
• How should we understand the scientific, historical, and theological truthfulness of Scripture?
• What is the place of the Bible within Christian discipleship?

God

Just as the biblical story begins with the creative acts of God in Genesis 1 and 2, the theological story the Bible centers on who God is and how he relates with humanity. Questions about who God is have remained some of the most important in all of Christian theology:

• Who or what is God?
• What are the character traits that best describe him?
• In what ways is God like us?
• In what ways is he not?
• What is the Trinity and how does it describe the nature of God?
• How did God create the universe?
• How is God sovereign over history?
• How can we communicate with God?

Jesus

The central figure of Christian history is the Second Person of the Trinity—Jesus. Fortwo thousand years, theologians have debated who Jesus is, why he mattered, and why he continues to matter today. The most important theological questions surrounding Jesus are:

• How should we understand the divinity and humanity of Jesus?
• In what way did Jesus exist before coming to earth?
• How should we understand the incarnation of Jesus?
• What was the meaning of Jesus’s life, death, and resurrection?
• What did the death of Jesus mean for the original readers of the New Testament, and what does it mean for us today?
• In what ways did his death atone for human sin?
• What was the nature of Jesus’s resurrection, and what does it mean for us today?

The Holy Spirit

Of the three persons of the Trinity, the Holy Spirit has likely been the most neglected in theological study throughout church history. Today, with more attention on the doctrine of the Holy Spirit, it’s one of the most hotly debated and divisive in the church. You’ll find broad agreement on some of these questions but also significant differences:

• In what ways did the Holy Spirit act prior to the day of Pentecost as described in Acts 2?
• What does the Bible mean when it describes the filling of the Holy Spirit?
• What are the gifts of the Holy Spirit, how are they distributed, and what are they used for?
• How do we understand the charismatic gifts of the Spirit, and what is their place in the church today?
• What is the unique role of the Holy Spirit in spiritual growth and the ongoing life of the Christian?

Humanity

Humans have long questioned how they came to exist, why they exist, their purpose, and the nature of the obstacles that prevent them from achieving their purpose. While those issues were debated long before Christian history began, they’ve been among the most hotly discussed in church history as well. These questions include:

• What is the purpose of humanity?
• What is sin and how does it impact humans?
• Why did God create humans both male and female, and are their roles intended to be the same or complementary?

Salvation

Because of the eternal consequences of theological discussion around salvation, the doctrine of salvation is particularly disputed in the contemporary church. The doctrine of salvation contains some of the widest areas of disagreement among orthodox Christians. Some of the most important questions in this doctrine are:

• Why do humans need salvation?
• How did Jesus’s work on the cross provide for human salvation?
• What is the gospel?
• What is election, and when does it happen?
• What is the order of salvation?
• What is the nature of the afterlife, and what determines the experience of the afterlife for humanity?
• What, if any, is the human role in salvation?

Church

Most divisions within church history have resulted from disagreements on ecclesiology (the theological study of the church). Therefore, the doctrine of the church has historically been one of the most important theological topics. With the coming of the digital age and the church’s response to Western cultural changes of the past half century, new issues in ecclesiology have emerged. Some of the most important questions for the church throughout the years have been:

• What is a local church?
• What is the nature of the universal church?
• What are the ordinances and/or sacraments of the church, and what is their significance for the church and for individual Christians?
• What are the offices of the local and universal church, and what are the qualifications for those offices?
• What are the roles of different officers of the local church?
• What is the purpose(s) of the church?
• Which, if any, are preeminent in the life of the church?
• What is the role of the church and the nature of its mission in the world?

Last things

Historically, the doctrine of last things (or as others call it, the doctrine of Christian hope or eschatology) has had increased interest in periods of persecution and/or cultural estrangement. In recent years, particularly among evangelical Christians, popular-level books and films have helped to spur on discussions about these topics. Significant questions around this doctrine include:

• What is the Christian theology of time (linear vs. cyclical)?
• How should Christians understand the literalness of the biblical description of end-time events?
• When and how will Christ return?
• What is the millennial reign of Christ, and how will/does the church relate to it?

Resources referenced + others to help you study theology

Dig into theological resources to help you understand and communicate doctrine effectively.

Lexham Bible Dictionary

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Summa Theologica (22 vols.)

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Institutes of the Christian Religion

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Barth’s Church Dogmatics (31 vols.)

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Holman Illustrated Bible Dictionary

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The Oxford Dictionary of the Christian Church, rev. ed.

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The Westminster Dictionary of Theologians

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The Bondage of the Will

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New Dictionary of Theology: Historical and Systematic, 2nd ed.

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Systematic Theology: An Introduction to Biblical Doctrine, 2nd ed.

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Theology: Foundational Certificate Program

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Bonhoeffer for Armchair Theologians

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Systematic Theology: An Introduction to Christian Belief

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Dictionary of Theological Terms

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Pocket Dictionary of the Reformed Tradition

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The Thiselton Companion to Christian Theology

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The practice of developing theological convictions isn’t primarily an academic exercise—it’s a spiritual one. Truth—the kind of truth that changes lives—comes from God and him alone. John the Baptist understood this when he said: “No one can receive anything unless it has been given to him from heaven” (John 3:27 CSB).

Invite God into your theological reflection from the start. Let him know you want to know him. That’s why you’re studying theology. Ask him to open your mind and your heart to truth from his Word.

After talking to God about your theological study and dedicating it to him, search the Bible. God’s Word doesn’t just inform our theological convictions. It’s the basis for them. All we know about the doctrines of Christianity flow from Scripture.

As you try to understand what the Bible says about a specific topic, you’ll want to take a “verse-with-verse” approach that looks throughout Scripture to see what it says about the topic. At a basic level, a concordance can be a great way to start. A typical concordance will organize biblical verses by subject. Take the topic you’re going to study and look up a variety of verses on it and other related subjects. For example, if you’re going to study the topic of election, you might study what the Bible says about election, salvation, predestination, etc. Usually you’ll want to look at instances where the terms are used in various parts of speech (verbs, nouns, etc.).

But one of the advantages of studying theology in the twenty-first century is the ability to use digital tools to amplify your biblical research. Software like Logos gives you an opportunity to not only search the full swath of Scripture in a few taps but to add several digital tools to your Bible study. With Logos, you can study a passage in its original language (even with a limited language background), find related verses, and even see how others interpret the passage in just a couple of clicks.

While biblical research is always your starting point, involving the reflection of theologians from the past helps to ensure you’re staying within theological orthodoxy. For two thousand years, Christian theologians have studied and debated what Scripture teaches on important doctrines. You will not discover anything that is biblical and new to the church. You may apply Scripture to new problems, but you’ll never discover new theology.

That’s why it’s critical to see what church leaders have said in the past about topics you’re studying. Don’t just look at one era of church history either. It’s important to look at theologians from the Patristic, Medieval, Reformational, and the Modern eras of church history.

This is another area where digital tools come in handy. With Logos software, you can search theological resources for topics in a few simple clicks. You can also lean on the Logos Theology Guide to research theological topics in all of your resources. With the Theology Guide, you can easily move between various theological texts and compare views of theologians across different eras.

Writing down your theological convictions has multiple advantages. First, it allows you to clearly synthesize your thoughts. Documenting your doctrinal convictions forces you to keep a consistent and reliable argument as you describe your beliefs.

Writing your theology also helps you share it. While it’s important to study theology for your own spiritual growth, ultimately you want to help others to learn more about God through your reflection. Even if your plan is to share it orally (through a sermon, lecture, or speech), a well-written doctrinal description will help you do so. You may even want to distribute your theological reflection through a book, blog series, article, or some other public manner.

We are all theologians

Every believer throughout the ages who has ever cracked open a Bible is a theologian. As we read the Word to discover more about God and how he is at work in the world, we’re most assuredly “doing theology.”

But diving into the Bible is just the beginning of doing theology. When Paul described to young Timothy the goal of the Bible in 2 Timothy 3:16–17, he said: “All Scripture is inspired by God, and is profitable for teaching, for rebuking, for correcting, for training in righteousness, so that the man of God may be complete, equipped for every good work” (CSB). We study what the Scriptures say about God so that we might know God and do his work in the world.

As theologian Sam Storms once said: “The goal of theology isn’t knowledge but worship.”

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