The Authorship and Date of the Book of Acts
The book of Acts is a historical narrative of the early history of the Church. As such, the authorship and date can be established by evidence found in the book itself. In addition, outside sources such as other books of the Bible as well as history recorded by other historians of the time supplement the evidence give by the letter itself.
According to 2 Timothy 3:16 the original author of the book of Acts is God, however, God did not pen the book himself. A man penned the book as the Spirit of God instructed him. Luke, as the human author, has strong support as the author of Acts given his previous letter he penned to Theophilus about Jesus' ministry.
The wording in the first chapter of the book of Luke is interesting because not only does Luke address the same man as in the book of Acts, but he also gives a lengthy explanation as to why he is writing the letter. In that letter, Luke wants to compile a narrative about the things accomplished by "us" (Luke 1:1). In verse two of his book, he makes a clear distinction between the disciples who witnessed Jesus' ministry and "us". Then in verse three Luke takes a step back and tells Theophilus that since he had followed the testimony of Jesus' ministry closely, he wished to begin there rather than with his narrative on the things he and the Christians with him had accomplished. So then, where is the fulfillment of what Luke said in Luke 1:1 to Theophilus? The answer would have to be Acts as it begins a narration to Theophilus working off the groundwork Luke had already laid in his letter as well as revealing what the Church had done, which is what Luke had said he would compile and write in his first letter. Then the beginning of Acts the author refers to a first account consistent with Luke's book.
In the book of Acts itself, the narrator begins in chapter 16 to refer to Paul's traveling party as "we". This pronoun change indicates that the narrator at this point was accompanying Paul and continues throughout the rest of the book. When Paul mentions this part of his career in his own epistles, he mentions he is...