Here is a little of what Sanders has to say:
"The debate over whether or not Paul 'converted' is actually a debate about the meaning of the word conversion. If it means 'turn from the worship of one god to the worship of another,' then Paul did not convert. If it means 'turn from one set of religious practices to another set,' then one could argue that Paul partially converted, since... he sometimes gave up some Jewish practices...
"But, if by 'conversion' we mean not 'turn from,' but only 'turn to,' then we may say that Paul converted. He turned to a new revelation from the God of Israel, a revelation that transformed the old in a fairly radical way... My own inclination is to use 'convert' in the third way--turn to--and consequently to speak of Paul's conversion, but I would not wish to fight to death over this usage." (E. P. Sanders, Paul: The Apostle's Life, Letters, and Thought, (Minneapolis: Fortress, 2015), 101-102.)Now, I do not substantively disagree with anything Sanders says here. But, I still find the language of conversion problematic. If one defines conversion as Sanders does in his third definition, then of course Paul converted. Yet, the only problem is that this is not how most people, IMO, conceptualize the word conversion. I teach undergraduates as a full time job, and I understand that redefining words is not always successful. You need to work really hard to redefine words and concepts that are already embedded in a student's mind. I think that the common "street" definition of the word "conversion" is much more along the lines of the following definition from dictionary.com: "change from one religion, political belief, viewpoint, etc., to another." Specifically, within the context of Paul, I think many would take the word conversion to mean that Paul converted from one religion, Judaism, to another different religion, Christianity. Now, I do not think that you would find a single New Testament scholar that would agree with the preceding statement. Paul did not see himself as leaving Judaism. He had a "revelation" (Paul's word, apocalypsai, Gal 1:16), and that revelation dramatically transformed his understanding of the the God of Israel, nevertheless, it did not represent a conversion from one religion to another.
The problem, of course, is that today, Judaism and Christianity are legitimately two distinct religions. But this was not so in the first century. At their earliest stages, Christianity and Pharisaism (later Rabbinic Judaism) were competing forms of Judaism. So, to use the word conversion in the context of Paul is to confuse the issue, because to most people, they will hear this as a conversion from one religion to another, and that is not at all what was going on. Using the language of conversion for Paul perpetuates the worst in historical Christianity, the supersessionism and antisemitism, which is responsible for some of the worst injustices carried out in the name of God. Can we find a better word for what happened to Paul? One that will not carry on age old misunderstandings that have plagued Jewish and Christian relations for nearly 2000 years?
In my lectures on Paul, I have used the phrase, "change of heart," for what happened to Paul. Yet, even so, I am not sure that that phrase really captures what is going on with Paul. Does anyone have any other suggestions or ways that they have spoken about Paul's experience?