“why would he get turned off even more because his dating a girl who wants him to become religious?”
First of all, he’s not dating such a girl, nor do I think he wants one.
At present, he made a decision to go OTD. He’s not interested in religiousness. He probably does not want such a girl for an LTR.
“if he likes her enough why would he feel such a way?”
As I touched on above, most men don’t want to be changed. It turns them off. Simply put, that’s not accepting the man for who he is. Many women try to “improve” their men. Men hate it, as it’s demeaning.
“he should want to do anything for the girl he likes enough. “
Probably not (see what I just wrote). Maybe in very rare circumstances, but that’s not happening here. He’s not even dating you. In fact, you have not even mentioned that he shows any desire to date you. To me that’s enough to say that you are (pardon any negative connotations) barking up the wrong tree.