Is there Evidence that Allah Exists?

[littleendian]

Even if that was so, which I doubt, it's still only a theory, not proof.

Sorry friend, it is not an argument or just a theory
it is a proved theory, i.e. a fact (till it is refuted)

A theory remains a theory, there is no absolute proof for anything, even the laws of physics are only theories that have merely worked so far. The only progress you can make in your theory is by testing it against reality which will either reinforce your belief in it or show that it's wrong. There is no such thing as absolute, watertight proof.