The argument itself is simple. If you have seen or heard God, then you must believe in God. If you haven’t, then the only possible reasons to believe in God are reasonable argument or the testimony of others. The main argument given for believing in a deity – that the universe must have had a first cause – is not persuasive because there is no reason to believe either that the universe must have had a first cause or that this cause, if it existed, was a deity. The testimony of others – a third-rate source of knowledge in any case – is invariably contrary to reason. This is not least because it reports God as commanding belief, which would be irrational of God, given that belief is involuntary and not an act of will. So there is no reason to believe in God.