Luke tells us that Paul spent some time in Damascus proclaiming Jesus in the Synagogue, but was forced to leave the city because there was a plot to kill him (Acts 9:23-25). Paul mentions these events in Galatians and 2 Corinthians in far more detail. Luke compresses three years of ministry into a few lines!
How long was Paul in Damascus and the Nabatean kingdom? According to Gal 1:17 three years pass between the Damascus Road experience and Paul’s meeting in Jerusalem with Peter and James (Acts 9:26-30). Since the story of the escape over the wall is a unique event, it seems reasonable that Luke’s “many days” (9:23) extends a full three years. Since Aretas IV died in 39, the latest date for Paul’s conversion is 36, if not earlier.
After the initial confrontational ministry in Damascus, it is possible that Paul traveled from Damascus to other major cities in Nabatean territory. This likely included cities of the Decapolis, perhaps, Geresa and Philadelphia (modern Jeresh). Philadelphia was a large Roman city, the type of city Paul will target later in his ministry. It is possible he visited Petra since it was a major trading center at the time. He may have used Damascus as a “base” since there was already a community of believers there. We simply have no real facts to deal with for this three year period, other than he was living in that territory for three years and that he did not consult the other apostles until three years after his experience n the road to Damascus.
As James Dunn observes, the more difficult question is why Paul spent three years in the Arabia. Paul makes an emphatic statement that after receiving a commission from the resurrected Jesus to be the “light to the Gentiles,” he did not “consult flesh and blood” but went to Arabia (Gal 1:7). Like Dunn, I think that Paul is simply following through on the commission he was given, to take the message of Jesus the Messiah to the Gentiles. The Nabatean kingdom provided him with ample opportunity to do just that.
Sometimes this period is described as a spiritual retreat into the desert, to work out the implications of his encounter with Jesus. I think that it is certain that Paul begins working through what “Jesus as Messiah” means, and what his role as the ‘light to the Gentiles” should be. He likely spent a great deal of time reading the scripture developing the material that he will use later in Antioch, then on the missionary journeys. But this period is not a monastic retreat! Paul is preaching Jesus and being faithful to his calling as the light to the Gentiles.