What does God have to do with it?

Religions just say "Believe." How can I believe, when you don't give me anything to believe? Religion is completely without substance. If they say "believe in God and the message of this or that messenger of God," I would say "Why?" If they bring in miracles, I would give Hume's answer, including the fact that even if I personally saw a miracle, it would only prove something wrong with my senses; and also there is the fact that miracles do not prove the existence of a God, and so how can they prove somebody is a messenger of God? If in answer to my original question "Why?" they say "Because we believe in brotherhood and peace, and so on," I would say "I already believe in all those things, and they have nothing to do with belief in any God or religion I do not need God or religion to think and act as a mature adult human being. The basis of humanism is not a set of beliefs; rather, it is a mature realization of what it means to be a human being, namely to think and act rationally, or in other words not to act according to the whims and impulses. A rational agent is a moral agent, because a rational agent automatically behaves morally, that is, in accordance with principles of brotherhood, charity, and so on. Charity is based on faith in man, and hope for his future.