Critique and denial of metaphysical beliefs in God or divine beings.
Unlike agnosticism , which leaves open the question of whether there is a God, atheism is a positive denial. It is rooted in an array of philosophical systems. Ancient Greek philosophers such as Democritus and Epicurus argued for it in the context of materialism . In the 18th century Immanuel Kant , though not atheists, argued against traditional proofs for God's existence, making belief a matter of faith alone. Atheists such as Ludwig Feuerbach held that God was a projection of human ideals and that recognizing this fiction made self-realization possible. Marxism exemplified modern materialism . Beginning with Friedrich Nietzsche , existentialist atheism proclaimed the death of God and the human freedom to determine value and meaning. Logical {{link=positivism">positivism holds that propositions concerning the existence or nonexistence of God are nonsensical or meaningless.