Hard Evidence that the Book of Acts was Written by an Eyewitness?

Here is an interesting question I received about a Christian apologist’s argument that the book of Acts must be written by an eyewitness, a view that I think is completely wrong.  It’s one of those arguments that has no bearing on anything when you actually think about it, but until someone points out the flaw, it’s hard to see it — or I assume so since so many people get taken in by this sort of thing.

It comes in a book called I Don’t Have Enough Faith to be an Atheist, a title which, I have t...