do you have to be religiously or spiritually suited to the person you love to gain their trust and respect? being an atheist, what are my moral obligations to this man who holds high regard to religion and spirituality?

Interesting. I suppose that if "spiritually" is understood very broadly to mean something like having reverence, care, respect, an appreciation for some things being sacred like promise-keeping, honesty or respecting the integrity of others, then perhaps spirituality of this general sort might be essential (by definition) for trusting and respectful relationships.

On religion: some religious traditions (or traditions within the traditions, e.g. orthodox Judaism as opposed to liberal or reform Judaism) discourage practitioners / "believers" to marry outside "the faith" or the practice or the tradition, but "mixed marriages" (and thus relationships) seem more common.

On atheism: "Atheism" may be variously defined; minimally it might mean either someone who makes the positive judgement that there is no God or someone who simply does not believe there is a God. The difference is subtle and may make no practical difference, but the former "atheist" goes on record (so to speak) in affirming there is no God whereas the later may give the matter little thought. An analogy might be comparing a philosopher who is doggedly anti-Hegelian and goes our of her way to argue Hegel is wrong versus a philosopher who adopts a non-Hegelian philosophy but gives Hegel very little thought. The reason I bring this up is that "this man who holds high regard to religion and spirituality" is a theist, you might simply ask him whether it conflicts with his values if he is trusting and respecting a person (you) who either thinks his views are mistaken (this is the case of the affirmative atheist) or with a person who simply does not (at this time) share his viewpoint (theism). In either case, it is worth noting that, in Christianity anyway, it is often held that persons who do not share the theology of a tradition may (in practice) actually be more faithful in following the teachings of a tradition than the so-called "believers." I have an atheist colleague who seems more Christian in practice than one of my professing Christian colleagues, for example.

Good luck!

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