And one nation under God.

So I was driving the other day and was sitting at a red light. I noticed the car in front of me had a cover around the license that read "Gods opinion is all that matters".  I don't want to say that this bothered me, because I know everyone has there own views on life and that's totally fine. But I guess I don't understand why it has to be 'Gods opinion' that matters most. Why cant our own opinion be the only opinion that matters to us? That's how i see it, I mean I can't really see myself living my life the way a book tells me to live, that was written by a being that I don't even know exists. I think it is what I think is right and wrong... my own opinion. This is where I get lost in Christianity, so many people have different interpretations of God. For example I know of Christians who believe in gay marriage, but I also know other Christians that believe gay marriage is 'sinful'. So that just makes me want to ask the question... how can Gods opinion only matter when there are so many people who view 'God' differently? I just seem to find that all a bit ironic. 

Oh Religion, you're just a little to out there for me.