Looking at how the gods of the Eternal Continent have almost completely vanished from existence, it's easy to imagine just how devastating that war must have been.
During the Divine Cataclysm, the God King was slain by Zenobia, nearly all the gods perished, and only a few, like the Goddess of Dawn, managed to survive by the skin of their teeth.
As for Zenobia, the one responsible for it all, she was stripped of her divinity and forever sealed in the dark side of the Eternal Continent, which is now known as the Abyssal Demon Realm.
It wasn't that the gods were too merciful to kill Zenobia; it was that they couldn't. As long as desire and sin existed, she would never truly die.
The place where Luca now stood was the "Divine Court," the former home of the gods. However, this once heavenly sanctuary had long since been turned into a ruin during that great war, and later, it was overtaken by monsters.