I’ve made the argument that this is the greatest possible free world. I may get into that later. But the greatest possible world would not be the same as the greatest possible free world.
If there is an afterlife, it must be better or worse than this world.
If there is no afterlife, this would be the best [and worst] possible world by default. But you see, an atheist is correct either way. If there is an afterlife, this life is better than hell. And if there is no afterlife, this life is, by necessity, better than nothing.
If God exists, he exists in the greatest possible world. If there is an alternative worst possible world, God does not exist there. Because if he did, it could be worse. If God didn’t exist there.
But if you don’t believe God exists, he can’t exist in your ideal greatest possible world. So that, your greatest possible world is one where God does not exist. This is independent of the fact that God may or may not exist.
If there is a maximally great being, and the end game of humanity is to have them enter a maximally great world, it would make no sense to admit those who don’t believe in any such being or world. Because admitting people into that world who don’t think it’s the best possible world would make it less than the greatest possible world.