Yes, actually.
Stop.
His ideas may be born from years of religious indoctrination but they're still his ideas. They are still a part of him and if you love him (friend or otherwise) the you need to accept that as is, even if you hope for it to change at some point.
Change is a gradual thing. Change that involves deeply embedded shit like this? Even moreso.
Wanting to force a change just screams that you care about an imagined version of this person, rather than the actual person and that isn't healthy for anyone.
Continue down this forceful road and you will most likely just destroy your relationship and negatively influence both of your lives.
Consider this: Are they aware of who you are, including your sexuality? (Given that's your concern here) - If they are, and they accept you anyway, then they obviously care more about you than any "programming" already.
Let that blossom naturally and see where it leads. Trying to push something like this never ends well, at least in my experience.