Could you date or be in a a relationship with a theist?
Long term relationship, I’d have to think really hard about that. FWB, sure.
Been there, done that and it didn’t turn out very well because of religious differences. It’s not just the two of you. It’s family, friends and their church. Relationships take work and this just adds more stress. To each their own.
I could date a nun, as long she put out.
Could, yes. They are a dime a dozen.
Would I? No. I believe a positive relationship should be based on mutual respect and honesty. As an atheist, I can not respect a person who bases their belief system on the dishonest premise that faith (belief without evidence) is a methodology to determine (Truth) things that are testable and demonstrated to be correct with evidence.