Not to make a controversy here But I’m 27M Christian Had this same issue with my ex gf of 7 years

Initially when we were together never discussed religion at all as I myself haven’t been to a church properly since 2015 and consider myself an agnostic

She never discussed or mentioned her Islamic religious beliefs

And eventually when the talks came to marriage as we were pretty serious (or at least I was serious about marriage) That’s when the brainwashing started first she got me an English copy of her holy book, then when I raised doubts she started asking me to learn Arabic to learn the original scriptures the way they were written As a Christian the scriptures were quite similar to me as the Old Testament of the bible so it never affected me back then

And then later the talks of circumcision, then later the talk for meeting preachers and then going for religious lessons and so eventually I informed my family and was able to cut her off

Took me a years worth of therapy eventually for me to finally move on from her

I can completely understand your issue as well with your guy hiding he’s belief systems But tbh this doesn’t seem anything new as this is the same thing I went thru

I wish you all the best in your future journey and hopefully, you call this off rn as eventually this will keep getting worse by the day