Give him “The Salvation War” from Stuart Slate to read.
That will shut him up.
Sell it to him as a story about the rupture and the fight of the unbelievers against their destiny.
He will then find out that the story doesn’t play out like the bible told… as Humanity curb-stomps hell and heaven into dust without blinking. And if he ever dares to speak the topic again, cite the book. I personally love the part when a random US marine puts a janitor on Gods throne because that guy is the only one knowing what he is doing. Though the pope excommunicating god for being not worthy also has its merit. Ah, Satan gets it too. He hides in a dirt hole from B-52 bombers.