Even hell can't accept all sinners, especially when people exterminate each other. Hell could not be overcrowded and the flow of sinner must be stopped. Azrael and his scythe won't let any soul pass through the gates.
Hell is Full! Is that clear enough? The war on the surface of Earth has exterminated billions of people and their souls are heading straight to hell. You can't afford to accept them, so the biggest amount of that souls should be eliminated. Grab your scythe and cut them into pieces, but don't forget to use a special ability and turn into the demon for a few seconds.