In Acts 8:1 we are told that Saul (Paul) consented to Stephen’s death. This may indicate that he was a member of the Sanhedrin and was perhaps the prosecuting attorney. At this point, I wish to focus upon the year of his mission to afflict the Messianic believers at Damascus. It is worthy of note that the Apostles were not persecuted to the point of death; that is, their lives were not in danger. Why was this so? The only logical answer, as far as I can see, is that it was only that branch of the church to which Stephen belonged that was persecuted. The Grecian or Hellenistic Messianic believers had separated under good terms from the main body of Palestinian Messianic believers (Acts 6:1-6).
It was at that time that a large bloc of the priesthood who believed in Jesus joined themselves to the Apostles (Acts 6:7), implying that while the Hellenistic Messianic Jews were joined to the Apostles, these priests considered the body ceremonially unclean, probably due to the iffy traditions of the Hellenistic believers. Some may not have retained kosher eating habits, and most likely all were not as picky concerning the washing traditions of the fathers—the Oral Law—as the Apostles probably were. Remember Peter’s ministry (and therefore that of all the Apostles) was to the Jews, particularly those who lived in Judea and Galilee. It would be very difficult to minister to a society that considered you unclean. If most of the Palestinian Jews wouldn’t keep company with the Apostles, how could they understand and receive the Gospel? Therefore, those Apostles who did not ordinarily practice the Oral Law (cp. Mark 7:1-5) most likely submitted themselves to it in order to reach their Jewish brethren who were considering Jesus, and wondering if he were the Messiah. So at this point in Acts 6 we can see that the Messianic Jews have grown into a body which can be described as being composed of liberals (the Grecian or Hellenist believers), moderates (the Apostles and those close to them) and conservatives (those who were particularly sensitive to ceremonial washing etc., of which James, the brother of Jesus, would later be the head).
Therefore, Paul most likely pursued only the liberal Messianic Jews or only those who believed as Stephen. It was not, therefore, that Jesus’ resurrection per se was the reason for the persecution, because, remember, Paul was a Pharisee who believed in the resurrection. It was Stephen’s message, namely, that the Temple was not needed for men to walk with God that was so troubling. For religious Jews, the idea that the Temple was not needed was the same as saying the name of God, which was perceived to be upon the Temple, was not needed, and this amounted to blasphemy. All who held to this idea and preached it had to be punished.
According to Acts 9:1-2, Paul sought letters from the high priest to go to Damascus in order to arrest and return Messianic Jews to Jerusalem for judgment. This would have been unnecessary, unless there was a change in the office of the high priesthood, because Paul had already been harassing Messianic Jews for some time. Why would he need new letters, unless there would be reason to believe a possible change in policy had occurred at Jerusalem toward the Messianic believers? The fact that Paul knew there were Messianic Jews there shows some correspondence was exchanged and perhaps complaints were brought up between Damascus and Jerusalem.
Caiaphas was removed from office just after Pilate was replaced as procurator of Judea. Therefore, to understand the approximate time of Saul / Paul’s going to Damascus we need to know when Pilate was replaced as procurator. The death of Augustus occurred in August of 14 CE, however, Tiberius was co-regent with him for a year prior to his death and was ceremonially confirmed as Emperor by the Senate in September of 14 CE. He had been effectively in the office of Emperor, but without the official name, for a year. Nevertheless, Josephus counts his reign from his official entry into that office [Antiquities 18.6.10; cp. 18.2.2]. The point is, did Tiberius send Valerius Gratus to be procurator of Judea immediately or delay a year? Scholars believe he appointed Gratus a year later in 15 CE, and I see no reason to doubt this date, but it could have been done in 14 CE.