be sure of one's own mind. A person will never know someone else's mind all they will ever know is their own. This makes proving that other minds exist very difficult. This problem carries over to divine beings as well. For you and I will be less likely to ever know a divine beings mind then that of a human mind.
Another problem arises in that we can observe humans. Through observations we can apply minds to other people based on the best explanation argument. However, from as far as we know cannot observe divine beings in so the best explanation argument can't apply.
B. The problem in proving that divine beings can have minds is far more difficult then proving that other humans have minds. I say this looking past the obvious and foremost difficulty in that we (a human race) in so far as we know, have never come across a divine being.
A divine being from all accounts should be perfect. This however, causes a difficulty in that if a being is perfect can it have beliefs. A belief by most accounts is something that is mentally represented as true. Based on that account of what belief is, a belief can also be false. This however, cannot be for a perfect divine being, since the beings perfect.