... continued from yesterday.
Before we leave Acts 1, we should take a quick look at Theophilus, the individual to whom both Luke and Acts are addressed (Luke 1:3; Acts 1:1). It is possible, of course, that the name is purely symbolic. The name means "lover of God" and so both books could simply be addressed to all those who love God.
However, I wonder if Theophilus is actually the patron who supported Luke while he wrote these two books. If you look at some of the other literary works from the time, they were commissioned by various wealthy individuals. For example, Virgil, who wrote the famous Aeneid, was commissioned by more than one patron to write his books. A typical event would involve the patron throwing a lavish dinner for friends and inviting the writer not only to eat but to read the latest bit of his writing.
Now Luke-Acts has some of the strongest warnings about wealth, so it would be intriguing if in fact Theophilus commissioned Luke to write these two books. Together, they constitute a kind of history of the origins of "the Way" (cf. Acts 9:2), which seems to be what some of the earliest Christian Jews called themselves.  As we work through Acts, I'll suggest that Acts in particular has some of the characteristics of what we might call "apologetic history," which is when a group's story is told in such a way as to defend its reputation against some of its outside opponents.
We of course do not know for sure that the author's name was Luke. Neither the Gospel of Luke or the book of Acts mention who their author was. However, we don't know of any other name ever being suggested but Luke. There are a number of passages where the story changes from the third person (he did this, they did that) to the first person (we went here, we went there). It starts at a place called Troas (Acts 16:10), disappears for several years at a place called Philippi (Acts 16:17), then reappears at Philippi again (Acts 20:5) and continues until the end of Acts.
So it is reasonable to assume that the author of Luke-Acts was a sometimes traveling companion of Paul. Since Acts ends at Rome and since the early Christians thought Colossians was written then in Rome, just before Paul died, it is only natural that the tradition would pick someone in the closing greetings of Colossians as the likely author of Luke-Acts. Luke, the doctor's name is there. Whether this is good detective work on our part or whether we are simply repeating the research the early church did when it was trying to figure out who wrote Luke-Acts, we do not know.
We can be more certain about when Luke-Acts was written. You sometimes hear people say that Acts must have been written very early, about AD62, because that is where Acts ends. "Surely Luke would have told us," so the argument goes, "what happened when Paul appeared before Nero, if he had known." Some even go on to suggest that Luke-Acts might have been written as a kind of "amicus brief" to try to influence Nero's decision.
A key blind spot in this argument is that Acts was not written to tell us anything, at least not in the mind of its author.  It was written to an audience that presumably already knew the outcome of Paul's trial. Indeed, Acts gives us the strongest of hints as to what happened. Paul tells the Ephesians in Acts 20:25 that none of them will ever see him again (cf. 20:38). The final chapters of Acts are full of foreshadowing and foreboding. "Pity," the ruler Agrippa so much as says after Paul tells him his story, "he could have been set free if he hadn't appealed to stand trial before Caesar" (26:32).
The most natural way to read Acts is to conclude that Paul died after he appeared before Nero, which is generally how Christians took Acts until the twentieth century. Luke did not need to tell Theophilus this fact because he and his audience already knew. Not only would Luke have had to cut out other material to tell about that trial--Acts is about as much as could fit on a large ancient scroll. But it would have ended the story on a downer. When you consider that one of Luke's hidden agendas may have been to show that Christians are not troublemakers, how much more effective to end with someone like Agrippa in effect pronouncing Paul's innocence!
In the end, there are nearly definitive reasons to believe that Luke-Acts was written after Jerusalem was destroyed in AD70. The first has to do with the likelihood that Luke used Mark as a primary source, a position that the vast majority of experts on the gospels have held for well over a hundred years. The reason is the great similarity in wording and arrangement between the two. 
A subtle hint of this fact is in the way Luke 21:20 paraphrases Mark 13:14, which predicts that an "abomination that causes desolation" would be set up somewhere it shouldn't be. It is an allusion to Daniel 11:31, where the temple in Jerusalem is defiled by a foreign army. In Mark, the prediction is worded very vaguely, and most readers probably would have thought it was talking about the temple being defiled.
But Luke paraphrases the prediction much more specifically and concretely. He is giving us something like "The Message" version. Instead of the temple, he writes about Jerusalem being surrounded by armies and the city being defiled. He is virtually painting us a picture of what happened in AD70 when the Roman armies surrounded Jerusalem. Again, the most natural conclusion is that Luke is paraphrasing the prophecy with all the benefit of hindsight. Such a dating fits perfectly with the fact that Luke used Mark, which itself we very easily might date to the late 60s or early 70s. 
Luke-Acts is God's word for us no matter what our leanings on these sorts of issues. But that does not mean, of course, that these issues are not significant. They affect the meanings and connotations we see in the words. Nevertheless, since we do not have complete certainty, we have to hang loose to them to some extent. It is a reminder that the Spirit is ultimately in control of what he does in us through Scripture, and we must leave a little room for surprise and mystery.
 While Matthew, Mark, and John seem to fit more into the category of biography. Luke-Acts seem to be more along the lines of a history.
 God of course had bigger plans.
 For more details, see my Jesus: Portraits from the Gospels (Indianapolis: Wesleyan Publishing House, 2013), ***.
 Again, see my Portraits, ***. Mark's aside to his audience in this same passage, "Let the reader understand" (13:14), may have been a hint that the events we was narrating were happening as he was writing (or that they had happened recently).