Ues, there is the theory that you cannot prove a negative is true. I'm not arguing one side or the other. I'm just stating that if you say there's never proof of non-existence they you also have to agree that there isn't proof of existence either. Yes, Christians can say god exists, and do not have scientific proof of that. But Atheists also say god does not exist, but do not feel the same responsibility or burden of proof that they project onto the believers.