Lebinitz thought, like Voltaire’s Pangloss, that we live in the best of all possible worlds.
He argued for God’s existence by using the ontological argument, which shows that the idea of a perfect being is possible. He wrote out a proof for this, including the quality of existence itself. Kant refuted it.
The cosmological argument says that everything in the world is contingent. It could have not existed. Therefore, everything in the universe must have sufficient reason to exist that is outside the universe, this sufficient reason is God.
Some theologians say that God is imperfect and this explains the existence of evil. But Leibnitz says that God made the most perfect world. That in fact, the greatest evils are necessary because without them, there wild not exist the greatest possible good.
For theology, the evil that exists is a consequence of free will. But the opposite argument, Russel holds, is equally true. That the world is the worst possible world and was created by an evil God, that the good of the world exists only to heighten the evil in it, and that free will exists only to ensure sin.
People want to believe the world is good so they will accept bad arguments for it. The world is partly good and partly bad and no problem of evil arises unless this fact is denied