The Argument for Atheism from the Amazingness of God
This is a pragmatic argument for atheism.
God, as generally conceived, is the omnipotent, omniscient, omnibenevolent creator of the universe. We don't see God, but we see the universe. When we look at the universe, we see it is immense and complex with all sorts of phenomena, so much that it is hard to accept its existence. According to the definition of God, he is much greater and so much harder to accept than the universe. Why double our explanatory burden by positing God exists? So God is less believable than the universe. And the more we find out about the universe, the harder it is to believe in it, though we do accept it because of the evidence. So the more we find out about the universe, the less we can believe in God.
Edited to add this clarification: My argument says "if God is more unbelievable than the universe, then the more unbelievable is the universe, the more unbelievable is God." I'm arguing from the common theist definition of God as "that than which nothing greater can be conceived".