The earliest extant copy of this book of the NT appears in a document known as Papyrus 45, a manuscript written during the 3rd cent. In this manuscript, which contains portions of 14 chapters of the book, the title is given simply as Praxeis, "Acts." The same brief title appears in the Sinaiticus a century later. Other ancient titles are "The Acts" and "Acts of the Apostles." The writer himself seems not to have provided his work with a title, but was content to indicate only that he had addressed a "former treatise" to his friend Theophilus in addition to the one he now proceeded to write. The narrative of his "former treatise"--the Gospel of Luke (Acts 1:1 2; cf. Lk 1:1 4; 24:50 52)--closes with the ascension of our Lord, the point at which this latter "treatise" takes up the narrative (Acts 1:4 11). The book of Acts is not an exhaustive record of the post-ascension ministry of any of the apostles, and mentions only a few of them by name. It seems not to have circulated among the early Christian communities at quite as early a period as the Gospels and the Epistles, but it was, nevertheless, in general use by the middle of the 2nd cent., as writings such as those of Justin Martyr testify. Toward the close of the same century Irenaeus (Against Heresies i. 23. 1; ii. 20. 2; etc.) cites the book as Scripture, and its title appears in the first known list of NT books, the Muratorian Fragment, dated about the same time.
Although the writer of the book of Acts does not identify himself directly, he does provide at least three indirect clues which leave no doubt that he was none other than Luke, the writer of the third Gospel: (1) He is the same person who wrote a "former treatise" on the life of Christ and addressed it to a certain Theophilus (Acts 1:1 2; cf. Lk 1:1 4; 24:50 52). (2) In certain passages (Acts 16:10 17; 20:6 16; 21; 27; 28) known as the "we" sections the author was a member of Paul's evangelistic company. Paul repeatedly mentions Luke as one of his companions during the later part of his ministry (Christ's Object Lessons, 4:14; 2 Ti 4:11; Phm 24). (3) The language, diction, and style of the Acts corresponds closely with that of the Gospel of Luke. From the very earliest times Christian writers speak of Luke as the author.
The book of Acts was, in all probability, written by Luke at Rome during the two years of Paul's first imprisonment there, a.d. 61 63. Of this, the way in which the narrative breaks off abruptly soon after the arrival of Paul in Rome is almost conclusive evidence. The author having followed the labours of the great apostle to the Gentiles from the very beginning, often in great detail, it would be strange indeed if he said nothing of the outcome of Paul's first trial before Caesar, of his later ministry, second arrest and imprisonment, and execution--if these events had already occurred. Apparently Luke told no more in the book of Acts because, at the time he wrote, there was no more to tell. As to his reliability as a historian this has been fully vindicated at every important point.
In his introduction the author of the book of Acts implies that his objective is to provide a continuation of his earlier narrative, the Gospel, in order that the two treatises, taken together, might constitute a rather complete historical account of the origin and growth of the Christian religion. He proposes to relate how the gospel found its way from Jerusalem to Judea and Samaria, and eventually "unto the uttermost part" of the then-known world (Acts 1:8). To begin with, there were no more than about 120 members of the church (v 15), all loyal adherents of Judaism. But the infant church grew rapidly, at times almost explosively, in membership, and, hesitatingly at first, accepted proselytes and then Gentiles into its fellowship. Like the ever-widening ripples from a pebble cast into a quiet pond, the church reached out to a waiting world, first to nearby regions and then to lands afar. The story of how all this came about--how an insignificant Jewish sect became a world religion--forms the theme of the book of Acts.
The book naturally falls into two major divisions: (1) chapters 1 12, in which Peter is the leading character, and (2) chapters 13 28, where Paul is the focus of attention. The first section records the development of the church at Jerusalem (chs 1 7), its expansion into the neighbouring regions of Judea and Samaria (ch 8), the conversion of Saul (ch 9) and of Cornelius (ch 10), the acceptance of the first non-Jewish converts by the church at Jerusalem (ch 11:1 18), and the establishment of the first Gentile church, at Antioch in Syria (vs. 19 30). The second section covers the ministry of Paul to the heathen of the Roman world--his 1st Missionary Journey, to Cyprus and Asia Minor (chs 13:1 to 15:35), his 2nd Missionary Journey, that took him into Macedonia and Greece (chs 15:36 to 18:22), his 3rd Journey, much of which was devoted to Ephesus and the Roman province of Asia (chs 18:23 to 20:3), his return to Jerusalem and arrest there (chs 20:4 to 23:30), his imprisonment at Caesarea, appeal to Caesar, and journey to Rome (chs 23:31 to 28:31).
Horn, Siegfried H., Seventh-day Adventist Bible Dictionary, (Washington, D.C.: Review and Herald Publishing Association) 1979.