I was catching up with Larry Hurtado's blog and found a link to an interesting post discussing why Paul had persecuted Christians prior to his conversion, which is serendipitous for me since I've been thinking about this lately myself and have a different idea.
Hurtado writes:
In sum, it seems to me that both the nature and the cause(s) for Paul’s initially violent opposition to the Jewish Jesus-movement were somewhat different from the nature and cause(s) for the synagogue floggings that he later received in the course of his ministry as apostle. I’m inclined to think that Paul’s initial Pharisaic zeal was incited, at least in part, by the christological claims and accompanying devotional practices that he later came to embrace, and that are reflected in his letters. Indeed, his zealousness for his religious traditions may have even made him particularly sensitive to the implications of the christological claims and devotional practices of the early Jesus-circles ...
https://larryhurtado.wordpress.com/2014 ... re-causes/
I'm thinking Paul's persecution of Christians could have more to do with the Christian rejection of the Pharisees' oral Torah (as per, for example, Mk. 7:13: "you nullify the word of God by your tradition that you have handed down. And you do many things like that”), since Paul says he was "extremely zealous" for this tradition right after saying that he had persecuted Christians in Gal. 1:13-14:
For you have heard of my previous way of life in Judaism, how intensely I persecuted the church of God and tried to destroy it. I was advancing in Judaism beyond many of my own age among my people and was extremely zealous for the traditions of my fathers.
As Josephus says, these traditions were the law of the land (and presumably considered divine, as per rabbinic writings) during Jesus' time.
Ant. 13.10.6:
... the Pharisees have delivered to the people a great many observances by succession from their fathers, which are not written in the laws of Moses; and for that reason it is that the Sadducees reject them, and say that we are to esteem those observances to be obligatory which are in the written word, but are not to observe what are derived from the tradition of our forefathers. And concerning these things it is that great disputes and differences have arisen among them, while the Sadducees are able to persuade none but the rich, and have not the populace obsequious to them, but the Pharisees have the multitude on their side.
One might ask why the Sadducees weren't similarly persecuted for rejecting the oral Torah, but Josephus does say that "great disputes and differences have arisen among them," and that they were "able to persuade none but the rich," and, what I think is the key, bearing in mind the large crowds that Jesus attracted and the popularity of the Fourth Philosophy, they "have not the populace obsequious to them." Being rich, they were in a better position to defend themselves, and being unpopular, they weren't much of a threat. And as Josephus says in Ant. 18.1.4, they were also willing to go along with the Pharisees' program:
But they are able to do almost nothing of themselves; for when they become magistrates, as they are unwillingly and by force sometimes obliged to be, they addict themselves to the notions of the Pharisees, because the multitude would not otherwise bear them.
Contrast this attitude with Jesus', who over and over is not afraid to tell the Pharisees (and their cohorts) exactly what he thinks of them and their oral Torah (while emphasizing the written Torah). And as he says in Mt. 5:19-20:
Therefore anyone who sets aside one of the least of these commands and teaches others accordingly will be called least in the kingdom of heaven, but whoever practices and teaches these commands will be called great in the kingdom of heaven. For I tell you that unless your righteousness surpasses that of the Pharisees and the scribes, you will certainly not enter the kingdom of heaven.
So I reckon that for someone like Paul, who was "extremely zealous for the traditions of my fathers," this position would have been quite offensive. And I don't see why, as a Pharisee, he would have had any issue with their "christological claims" when the Pharisees (to judge from rabbinic writings) were messianic too. The situation is similar to the Fourth Philosophy, which rejected the oral Torah but otherwise "agree[d] in all other things with the Pharisaic notions" (Ant. 18.1.6), which presumably included messianism given what Josephus says in War 6.5.4:
But now, what did the most elevate them in undertaking this war, was an ambiguous oracle that was also found in their sacred writings, how, about that time, one from their country should become governor of the habitable earth.
I'm unaware of anything in Josephus that indicates that the Pharisees had an issue with the use of this oracle (aside from perhaps the timing of it and the militancy behind it). So why would Paul, especially considering the relatively peaceful position of Christians (e.g., Mk. 14:48 and 1 Peter 2:13-17)?
And Josephus himself was a Pharisee (who had joined and then rejected the Fourth Philosophy), and he used the same "ambiguous oracle" and applied it to Vespasian! Yet he over and over castigates the Fourth Philosophers for their "innovations" ("which we were before unacquainted"), such as their rejection of sacrifices on behalf of Gentiles, which he says was "customary" for Jews to offer in War 2.17.2:
... Eleazar, the son of Ananias the high priest, a very bold youth, who was at that time governor of the temple, persuaded those that officiated in the Divine service to receive no gift or sacrifice for any foreigner. And this was the true beginning of our war with the Romans; for they rejected the sacrifice of Caesar on this account; and when many of the high priests and principal men besought them not to omit the sacrifice, which it was customary for them to offer for their princes, they would not be prevailed upon. These relied much upon their multitude, for the most flourishing part of the innovators assisted them.
But concerning the "ambiguous oracle," he says that "God takes care of mankind, and by all ways possible
foreshows to our race what is for their preservation," so he clearly did not regard messianism as something "which we were before unacquainted."
So I think that Paul, as a Pharisee (and one who was "extremely zealous for the traditions of my fathers"), would have been more offended by the Christians' rejection of the oral Torah than by their "christological claims." The two go hand in hand: he says he persecuted the church and was extremely zealous for the oral Torah.