After Paul returned to Damascus from Arabia, he began to preach in the synagogues there. At that time there were thousands of Jews and Jewish proselytes among the Damascenes for Josephus tells us that 10, 000 Jews were slain there during the Jewish revolt [Wars 2.20.2], and this appears to be men only, for in another place he says there were 18,000 slain and there included women and children [Wars 7.8.7], but this does not include Jewish sympathizers or God-fearers who worshiped among the Jews every Sabbath. So, evidently Paul had a great mission field here, near where he first came to know Jesus.
It may be that this was Paul’s first real opportunity to begin preaching his Gospel, according to what he had learned from the Lord through the time he spent among the Arabians in Nabataea. Some scholars believe Paul preached the Gospel in Nabataea, but I believe this presumes too much of Paul to eject the Jewish traditions that had no value in his Gospel and to reconsider those that would have great significance in his effort to reach the Jews in Diaspora and the Gentiles in the Empire. Am I saying Paul didn’t preach at all in Arabia? No, I think he probably did some preaching before he returned to Damascus, but I believe the better part of his stay in Arabia was spent in study and contemplation. Remember, Paul’s life was turned upside down in a moment—in a twinkling of an eye, as it were. He had no time to consider what was wrong about his faith, only that he was indeed wrong. Paul had at least as much to unlearn as he did to learn, so a good portion of the three years between his heavenly vision and his first visit to Jerusalem would have been spent preparing the Gospel he would soon preach to the Gentiles to whom Jesus had called him.
Nothing is said of Paul preaching in Arabia, nor is anything said of his success in Damascus. However, I don’t believe there is any reason to suppose he didn’t preach in Arabia at all or that no fruit was gleaned for the Gospel during his three years before going to Jerusalem. Did this fruit include Gentile God-fearers? If we are to take seriously that Paul is the Gospel to the Gentiles, I believe it is only reasonable to assume some of the disciples won for Christ would include Gentiles, Peter’s ministry in Acts 10 notwithstanding.
In any event, Paul got into trouble while trying to prove to the Jews in Damascus that Jesus was the Messiah they awaited. Acts 9:23-25 says Paul’s trouble came “after many days had past.” This probably refers to a few months of ministry there among the different synagogues. Gradually, opposition arose until there was a band of Jews seeking his life. The problem some scholars see in this comes from Paul’s mention 2Corinthians 11:32 that Aretas’ governor in Damascus waited at the gate to seize or arrest him. What authority did Aretas have in Damascus? Perhaps none, but he did have a fair amount of influence with the authorities there, in that the trade routes from east and west went through his territory. The term governor in Paul’s letter probably means ethnarch, who acted with some authority within the city like an ambassador would today. He also probably had a military detachment under his authority which he used not only for his protection but also (for a price) to guide and protect caravans going through Nabataea.
The question is how did Paul get in trouble with the Nabataean ethnarch? Did Paul get himself into trouble while in Nabataea, so that Aretas was seeking to apprehend him? The text isn’t clear about this point, but I believe Paul’s troubles were local—arising from his stay in Damascus. Consider this possibility: it may have been that the Nabataean ethnarch was a Jewish proselyte or sympathizer / God-fearer who was offended in Paul’s teaching. Remember, the Nabataeans were near relatives to the Jews and the ethnarch may have been under the friendly influence of the Jews there. So, he may have been using his influence and authority on their behalf and not necessarily under the orders of Aretas.
On the other hand, if the ethnarch viewed Paul’s message as that of a political agitator, he may have desired to arrest Paul on those grounds, undoubtedly with the cooperation or approval of the local authorities. Aretas’ influence in Damascus would have been enlarged in light of his recent victory over Antipas, and the fact that Rome didn’t punish him would have only added to his influence in the area. If the ethnarch was a Jewish sympathizer / proselyte, he would have had two possible reasons to apprehend Paul. First, Paul was a renegade preaching against Jerusalem’s hard-line authorities. Secondly, as a Nabataean patriot, he would not have taken Paul’s preaching of a new King lightly. He would have at least desired to apprehend Paul for questioning before Aretas.