I only remember the arc where he transmigated to some believer(or something close to it) in the light church(?) and hypnotized himself to truly believe in that god because of certain benefits and later that personality was the main one until (i think) he met a dark god, and the dark god and light god are actually the same person with split personalities. sorry for the grammar and fussy memory and details.
Not 100 percent sure but might be from one of the arcs from https://www.novelupdates.com/series/quickly-wear-the-face-of-the-devil/