Imagine a person who comes in…and argues ‘no air exists’ but continues to breathe air while he argues. Now intellectually, atheists continue to breathe – they continue to use reason and draw scientific conclusions [which assumes an orderly universe], to make moral judgments [which assumes absolute values] – but the atheistic view of things would in theory make such ‘breathing’ impossible. They are breathing God’s air all the time they are arguing against him. ― Greg L. Bahnsen (from, Presuppositional Apologetics: Stated and Defended)