If I say I don't believe in Zeus, Artemis, Apollo, Mithras, Thor, Odin, Freya, Baal, Osisis, Ra, Quetzalcoatl, Toutatis... I'm am just a normal person, I'm never asked to justify my position or prove my non-belief. But if I say I don't believe in God, suddenly I'm am atheist. Atheism is a default position from which faith is a deviation.