What is God?

There are a number of conceptions of 'God' each peculiar to a religion. A prevalent conception of 'God' is of a supreme being with a number of different properties like omnipotence, omniscience, infinite goodness, and a number of others. But that is the concept of God. So the concept of 'God' certainly exists. However, whether anything answers to that concept, or any other concept of 'God' is a very different matter. That is the matter of whether there is a God, or whether God exists. We should never confuse the concept of 'God' with God, and think that because the first exists, so does the second. That would be a mistake in logic.