Call for Peace

I don't really understand what your question is. But, no ~ having only one God is not common in all religions. There are many many religions out there. Some have only one God. Some have one God and one Goddess. Some have multiple gods/godesses. And, some have no god/gods at all. If a person does have a religion, they do tend to accept the things that are common, basic, etc. within the confines of their religion. Otherwise, they would not count themselves a member of that particular religion. If a person does not have a religion, or spiritual belief system, they still adhere to whatever it is they do believe (even if that is "nothing"). So, again, could you elaborate on your question a little?