The Book Of Acts answer a theological problem, namely how the Messiah, promised to the Jews, came to have an overwhelmingly non-Jewish church; the answer it provides, and its central theme, is that the message of Christ was sent to the Gentiles because the Jews rejected it.
Acts of the Apostles, the second part of the work that begins with the Gospel According to Luke, is the story of the early church after Jesus’s martyrdom. Like Luke, Acts is addressed to the unknown reader Theophilus, and in the introduction to Acts, it is made clear that it is a continuation of Luke: “In the first book, Theophilus, I wrote about all that Jesus did and taught from the beginning until the day he was taken up to heaven” (1:1–2). Second-century Christian tradition identifies the author of Luke and Acts as Luke, a traveling companion of the missionary Paul of Tarsus. Modern scholars agree that Acts and Luke should be credited to the same author, but have been more reluctant to identify him: the author most likely wrote between the years 80 and 90, and may indeed have been Paul’s companion.