The author of the third Gospel and of the Acts of the Apostles never names himself. However, the early Christian tradition unanimously attributed these two works to Luke, a travel companion of the apostle Paul. This identification is confirmed by several internal and external clues.
Paul mentions a certain Luke several times among his co-workers. In the epistle to the Colossians, he affectionately calls him “the beloved physician” (Colossians 4.14). He also appears alongside Mark and other companions in the epistle to Philemon (Philemon 1.24). Finally, in his last letter, written shortly before his execution, Paul observes with emotion: “Only Luke is with me” (2 Timothy 4.11).
The book of Acts itself contains several passages written in the first person plural (“we”), which suggests that the author personally accompanied Paul on some of his missionary journeys (Acts 16.10-17; Acts 20.5-15; Acts 21.1-18; Acts 27.1-28.16). These sections, commonly called the “we passages,” constitute one of the main arguments in favor of identifying Luke as the author of Acts.
In all likelihood, Luke was of Gentile origin. In the epistle to the Colossians, Paul distinguishes his co-workers of the circumcision from those who are not, and Luke is not among the former (Colossians 4.10-14). He would thus be the only non-Jewish author of the New Testament.
His level of culture appears to be high. The quality of his Greek, his interest in historical, geographical and medical details, as well as his method of inquiry, testify to a solid intellectual formation. From the very beginning of his Gospel, Luke states that he undertook “exact investigations” and consulted eyewitnesses in order to write an orderly account addressed to Theophilus (Luke 1.1-4).
The Christian writers of the 2nd and 3rd centuries, notably Irenaeus of Lyon, the Muratorian Canon, Clement of Alexandria, Tertullian and Eusebius of Caesarea, unanimously attribute the third Gospel and the Acts of the Apostles to Luke, a companion of Paul.
Thus, Luke appears as a Christian of Gentile origin, a physician by profession, a faithful co-worker of the apostle Paul and a careful historian of the origins of Christianity. His two-part work, the Gospel according to Luke and the Acts of the Apostles, makes up nearly a quarter of the New Testament and is one of the most important sources for our knowledge of the life of the Messiah Jesus and of the beginnings of the Church.