Something interesting happens in most high fantasy and science fiction settings. Capital-F Faith in an absentee God who may or may not exist is absent. In Dungeons and Dragons, the gods exist. If you want proof, watch a paladin lay on hands. Science fiction settings can be a little looser with divine intervention tropes, but a sufficiently advanced AI is a reasonable substitute for a supernatural entity, and for ordinary NPC plebes, even modest mutant, cybernetic, or technological abilities are sufficiently advanced to provide a reasonable stand-in.

Having trouble finding the soul of your fictional society? Have you considered their fundamental rule-making process? Why not take a little time to suss the foundations of your make-believe culture by drafting their constitution? You might find that specific laws, mores, and cultural habits are easier to develop when you have a framework for decision-making and conflict resolution.

You can create reasonably immersive, fairly convincing setting by remembering a simple five-letter acronym.

MERPS: Social, Political, Economic, Religious, and Military.

From tiny little subsistence bands to mighty intergalactic empires, from sword-and-sorcery barbarian epics to swashbuckling adventure on the high seas, these five dimensions allow you to cover every major aspect required to create conflict and a memorable story.