If my interlocutor desires to convince me that Jupiter has inhabitants, and that his description of them is accurate, it is for him to bring forward evidence in support of his contention. The burden of proof evidently lies on him; it is not for me to prove that no such beings exist before my non-belief is justified, but for him to prove that they do exist before my belief can be fairly claimed. Similarly, it is for the affirmer of God's existence to bring evidence in support of his affirmation; the burden of proof lies on him.