But then he was also descended from said deity, so celestial-bloodline sorcerer would also make sense?

And through weird extradimensional time shenanigans he is also said deity? I don't understand it myself, but I'm told it makes sense in 12 dimensions.

He was also briefly undead, likely a revenant given the unfinished business.

All of this depends on the edition of the lore you read though. In the beginning he was probably just a warlock multiclassing in cleric, then a supplemental edition has him ascend to demi-god status, which was later ruled actual divinity by a local authority once the franchise changed hands. Later, some of it was retconned and toned down for being too OP in another rulebook, but famously that rulebook wasn't very well accepted even though a sizeable playerbase still exists.

There are later editions where the pathway to divinity is laid out and Jesus is one of many gods, but that rulebook is still considered niche despite some disproportionate influence.