Belief is a powerful thing. It shapes the past as well as the future. Once a thing is done and thousands of years have passed, who is to say the manner in which it came to pass? History is what we believe it to be just as God and heaven are what you believe them to be, well, to a point. God does have a definite nature. It's his appearance that changes. Your faith shapes it. There are many different heavens just as there are many different hells and many different types of angels.