Pretty much any evolutionary psychologist can tell you why imagination and joy are adaptive, and can explain plausible ways that they could have evolved; and the better ones can tell you why we can’t know for sure and the kind of evidence we’d need to be able to tell (and why we can’t presently get it, and probably won’t ever be able to get it).

Nobody can mechanistically explain how joy or imagination works, because we don’t yet understand how the brain works in the requisite level of detail.

There’s nothing particularly wrong with being motivated by eternal mystery with intuitions of a loving God. People get motivations from all kinds of places. If you look up at the stars from the middle of the Australian outback, and go, Oh. WOW., and that motivates you to become an astronomer, great! Have at it!

Just don’t think that you have particular insight into, say, reproductive rights because of that experience, and we’re all good.