Today, Godfather is a generic title of a role one takes as a special place in the child’s life. It does not have to carry religious meaning or overtones at all, so before relying on google to weigh in on your feelings, you could simply ask him more questions on what his role is more specifically, and what the meaning of godfather is between them. Will he adopt this child if the ex were to die unexpectedly? That could be a thing. It depends on what they agreed on. You aren’t going to change this guy or his pre established relationship with a child who is important in his life. It’s selfish to want that, and it was a mistake of a man twice your age not to disclose this in the relationship sooner, as this is an important part of his identity and a responsibility he accepted years ago. You are allowed to have boundaries of what you’re comfortable with in a relationship. You’re 20, hung up on the god word being in the title of a word associated with him, on top of not having the same belief system which is generally another HUGE compatibility factor. Are you truly compatible with this man?—because this is a topic of comparability for HIM. If you can’t accept it and he’s unwilling to compromise his duties (which would be selfish to ask or demand of him, and this will obviously include him being around his ex in some capacity) then perhaps you have discovered several levels of incompatibility all at once that shows you two aren’t the best match.