"Luke proclaims Jesus as the Savior of the world. This Gospel presents Jesus as the climactic turning point in world history, and it sets the stage for Luke’s second volume—the Acts of the Apostles. In both books, Luke focuses on the mission of Jesus, which continues and expands with the Church, out from Jerusalem to the world (Luke 24:47). In Jesus, everyone—Jewish and non-Jewish alike—may come to salvation.
Early church tradition holds that both the Gospel of Luke and the book of Acts were written by Luke the physician, Paul’s frequent companion during his missionary journeys (Col 4:14). Early church history also says Luke was a Gentile (non-Jewish) and came from Antioch—where Paul spent a great deal of time (Acts 11:25–26; 15:35). These biographical details fit with the Gospel’s familiarity with Graeco-Roman culture and its emphasis on Gentiles becoming followers of Christ. The Gospel also uses very sophisticated Greek, including technical terms for ailments, suggesting that a well-educated person (like a doctor) authored it.
Luke identifies his primary audience and purpose in the opening verses: He is writing to Theophilus, to give him confidence regarding the events of Jesus’ life (Luke 1:3–4). The identity of Theophilus is unknown; since the name means “lover of God,” it’s possible that Luke uses it generically to address any believer. However, it’s more likely that he is writing to an individual named Theophilus, who may be the sponsor of the work. In any case, features in the Gospel suggest that Luke assumed both Jews and Gentiles would read it. He seems to address people curious about Christianity and its relationship to Judaism, often utilizing Old Testament Scriptures and motifs."

—Faithlife Study Bible, Lexham Press