Both Luke and Acts are addressed to Theophilus, whether understood as a real person or a literary device. In Luke, the purpose of the book is laid out in the introduction:

With this in mind, since I myself have carefully investigated everything from the beginning, I too decided to write an orderly account for you, most excellent Theophilus, so that you may know the certainty of the things you have been taught.

 

^{Luke 1:3-4 NIV (emphasis mine)}

However, Acts, while beginning somewhat similar to Luke, does not lay out a purpose statement at the front: "In my former book, Theophilus, I wrote about all that Jesus began to do and to teach..." The author simply transitions to his narrative (verse 4) mentioning one occasion.

This seems to somewhat leave us in the lurch as to why the author wrote this second book. What can be adduced as far as the author's purpose(s) in writing this book?

Both Luke and Acts are addressed to Theophilus, whether understood as a real person or a literary device. In Luke, the purpose of the book is laid out in the introduction:

With this in mind, since I myself have carefully investigated everything from the beginning, I too decided to write an orderly account for you, most excellent Theophilus, so that you may know the certainty of the things you have been taught.

^{Luke 1:3-4 NIV (emphasis mine)}

However, Acts, while beginning somewhat similar to Luke, does not lay out a purpose statement at the front: "In my former book, Theophilus, I wrote about all that Jesus began to do and to teach..." The author simply transitions to his narrative (verse 4) mentioning one occasion.

This seems to somewhat leave us in the lurch as to why the author wrote this second book. What can be adduced as far as the author's purpose(s) in writing this book?