"Some theologians like to say that God does not exist. They say this to mark the radical difference between God and creatures. If one is going to say such things, a more helpful way to speak would be: "God exists but we don't." For that would still get across the radical difference between God and creatures, but get right the fact that God is the one who is the more real. Compared to God's reality, we are but shadows. It is said that God said to St Catherine of Siena: "I am who I am, and you are she who is not." This poetically conveys a deep truth. We are but shadows, and "shadow" is often an overstatement."
Alexander Pruss on his blog