I think another similarity not mentioned is that religions evolve and change over time, even those that claim that they do not.
The Bard siad: "A rose by any other name still smells as sweet." (or something to that effect). I think the same holds true for The Divine: it doesn't matter what you call Her as long as you call Her.
And, if my memory serves me well, all religions have some form of entity that is greater than man, regardless of what name they attatch to it. And, from somewhere I have heard that all men are created equal in the eyes of God.