Faster than 2120bc for a pantheon? Yes.
My first G&K game, not knowing what I was doing, founded judaism turn 71 epic pace (2200ish bc?). That was from a lucky hut, meeting a religious city state and putting my first settler near mt sinai. I thought that's just how religion was supposed to be lol. Then my next few games I got frustrated being unable to pick the pantheon I wanted, and realized I just got really lucky that first game...
... kinda like the thread with the guy playing spain that settled by great barrier reef and took one with nature, but I can't find it now...