Some people make the claim that God, a god, or some spirit being has communicated to them or to ancient people, but they have no proof of their claim.
What proof do you want? It must be measured, weighed, and labeled to prove existence is left-minded thinking, which is the very road block one must get past to find the proof you seek.
Furthermore, for someone to say "There is no God. There has to be some logical/scientific explanation for all things," is in itself a proof that such belief is based on faith. Faith is the cornerstone of religion.
Rather, to state "I have found no evidence of God. I will change my belief in God when I find evidence that suggest that," is a statement of open mindedness. It shows a person is capable of learning and growing. Of course, if you're not looking for proof how would you ever find it?
How does one prove God spoke to them? Isn't that a personal experience? I suppose that is the point. People are looking for some sort of intellectual explanation which is impossible. The only way to find it is through personal experience.