God and Satan Are Both Jerks: After the reveal that Christian theology is in fact true, it means that it was indeed the Christian God that has unleashed a series of horrors upon the Earth for the unspeakable crime of a few people believing in certain New Age trends, while the Antichrist has been successfully deceiving the world by harnessing humanity's anger for all of this for some apparent power trip he gets out of damning people to eternal damnation. Keep in mind, billions of people were killed or tormented in horrific supernatural ways indiscriminately, including newborn babies and children. Almost makes the the antichrist's death camps for Christian dissidents look merciful by comparison. In summary God will do horrible things to the world for no good reason, but one should worship Him anyway. And with Christianity being true, that means that all those people killed are now in Hell suffering for eternity. The only response? "Oh well, they had a choice. God feels bad about it."
Nightmare Fuel: Many of the disasters arguably qualify as this, but foremost is probably the mass Demonic Possession which turns hundreds of millions of people into senselessly murderous madmen, with graphic descriptions of how whole families bite, tear and strangle each other to death. Also, the plague of darkness is made up of literal Nightmare Fuel, an oozing blackness that engulfs everyone on Earth and causes them to experience pure terror and hallucinate dangers mere inches away from the person's helpless body. Anyone trapped in there would gladly commit suicide just to escape the fear.
Also, the description (albeit sanitized) of the Antichrist's death camps for Christian dissidents.