I only have one answer, fren. Boiled down, spiritual fulfillment can only come from having a personal understanding and relationship with a God you understand. People worship god, elohim, vishnu, allah, jesus, and those are all relatively modern. Think of the countless gods that were forgotten, they number in the millions. I say all of those people are/were right. It's only complicated because we make it complicated. One thing I am absolutely sure of however, and that is that spiritual fulfillment should make give life here in this realm meaning, not whatever came before or comes next. It's a trap to think otherwise.