Even in Christianity that isn't how that works, and this guy, like most Christians, doesn't actually understand his religion. Probably never read the bible either. Just little portions here and there which is why they don't know their own religion. Then they proceed to complain about nonsense they made up, all on a fucking porn game, which, if they are religious they shouldn't be playing anyway.
I mean hell why even be a fan of DxD in the first place? It has "demons" as a separate race instead of being the "fallen angels" that they are. And fallen angels are a third race somehow... Get over it dude. Fuck.