Hello, I'm new . .

Just taking your post as an example.

Yes, you can say that you are making a game about Christianity, it’s not fine going into details and adding other personal comments.

This comment is a personal comment and is not necessary in a gaming/developing forum, but it’s acceptable.
If you add, ‘Christianity’ to that list, it could become bannable, because it clearly sounds like religious propaganda.

I hope you understand the difference between a descriptive comment and a personal comment/opinion.

I am making a game with a focus on Christianity = Ok
I am making a game with a focus on Christianity, because I am a devout Christian, or other reason no one needs to hear = Not OK

That’s general common sense, but of course every forums have their rules, and if a Forum don’t want you to use a certain word, you shouldn’t use it (even if it sounds a bit extreme).