Atheism

Atheism is, in a big sense, the absence of belief in the existence of deities. This rejection of belief usually comes about either through deliberate choice, or from an inherent incapability to believe religious teachings which appear literally incredible. It is not a lack of faith born out of simple unawareness of religious teachings. 

In a narrower sense, atheism is particularly the position that there are no deities. Most inclusively, atheism is just the lack of belief that any deities exist. Atheism is contrasted with theism, which in general form is the faith that at least one deity exists. Many atheists feel that atheism is a more prudent worldview than theism, and thus the burden of proof lies not on the atheist to contradict of God, but on the theist to give a basis of theism.