That's agnosticism not atheism. The definition of atheism is literally in the word a-theism, the opposite of theism. A theist believes there's at least one deity, an atheist believes the opposite, that there are no deities. An agnostic, in a sense, believes nothing. There's no proof God exists, there's no proof God doesn't exist so an agnostic makes no claims about God. By rejecting the the possibility of a God you're making a claim and without proof that claim becomes faith.