Simple idea: Play with whatever mythological or religious legend/story you want, but make it creative.

Saul and David but in modern times?  Sure.

Norse Mythology except Loki is the son of Odin and Thor is the one meant to incite Ragnarok? Whatever floats your boat, kid.

The gods of Native American and First Nation tribes duking it out? Do what you will!

The DC universe except they're all Greek heroes/gods now? I mean Wonder Woman is already sort of a part of Greek mythology so why the fudge not?

Basically, anything goes, so long as it's associated with a mythology or legend of a group of people. Have fun!