How can those of any religion be so sure they're right, even without evidence?

I just do what I believe is right for me, I firmly agree that there is no proof. I follow Wicca, and even if there are no gods, what harm can it do to respect our environment and fellow humans? I don't preach to anyone that they need to follow what I believe. It is simply how I feel, you can live your life any way you wish, it is your life and I am happy to stay out of it.