I am playing with Japan , it's very early, no Patheons, I discovered a natural wonder but it's nowhere near... and I just see I have +2.3 faith or so per turn. I wasn't paying attention when it started :/ What causes this?
There are several sources of faith in Civ 6 : Rise and Fall. In approximate order of availability : Natural Wonders like Graceful Arch which add faith to neighboring tiles , Friendly Huts which provide faith upon entry , Envoys at friendly City-States , Holy Sites with adjacency bonuses , Holy Site buildings , World Wonders , civilization-specific Improvements like the Sphinx , City-state-specific Improvements like Colossal Heads , and a few others which come later in the game.
It's possible to find or create several of the above in the first 50 turns. It's very good to be suzerain of La Venta.