Well, I think it is possible to find evidence concening God, but not possible to prove God.
Although God is of the metaphysical realm and humans are of the physical realm, these two realms don't remain inherently isolated. God does act in the physical realm, too, so we look for evidence of the work of the metaphysical in the physical realm.
Second, it is possible to look for scientific proofs of stories found in religious texts. These do make it possible to believe some of the stories contained in these religious texts.
But ultimately, since God is of the metaphysical realm, you may find evidence of God, but you can never prove something that lies within the metaphysical realm.
And that's where faith comes in...