Having faith and believing in a super natural god is above natural and science. God is supposed to be supernatural, something science doesn't study or understand. So technically there can be no scientific evidence for a god.
I wouldn't quite phrase it in that manner, but essentially I agree.
If Joe believes in god why do you feel he is wrong and you are right by not believing?
That seems obvious. Because I don't believe in God. Just like Joe think I am wrong and he is right, because he believes there is a God. Whether one judges another, or takes any action on that difference of opinion is quite a different question.
It actually seems to offend some that Joe believes in god. Why is that?
I wouldn't speak for others. I could care less if Joe believes in God or not. It's worth remembering that plenty of folks like 'Joe' find atheism at best distasteful, and at worst believe us servants of the devil. Are you as interested in that position, and what is your opinion on it?
Why do humans fight about what they believe?
Because belief informs action. If you want to argue that humans should all be pacifists, and there is nothing worth fighting over, I honestly get it. But 'beliefs' aren't some individual choice which live in isolation. They inform world views, decisions and actions.
Women are burned alive in Papua New Guinea on almost a daily basis, with various beliefs enabling that. Dealing with the crime and action itself is obvious, but should we not be interested in the root cause of such behaviour, or try to address it? Really?
Isn't what they believe a personal choice?
Of course. I make lots of personal choices all the time. I can decide whether I want tea or coffee, and I doubt other people care. However, if that equates to me using the last coffee pod in the house, my wife is impacted by my personal choice. It comes down more to the impact of belief on the world around me than whether I can hold a belief in and of itself.