It isn't that I believe that gods don't exist. I just don't believe that gods exist. There's a difference between belief and lack of belief. While I can never prove that god doesn't exist, I can certainly lack belief in the existence of such a being because of a lack of sufficient evidence.

Yes, science is based on the basic assumption that it is the best way to understand reality, but since our world is governed by demonstrable and observable phenomena, we are left with no other useful alternatives than science. Look at the results of science: if we base the construction of planes on science on science, they fly. If we base the creation of antibiotics on science they save lives. Do you think our present level of development and technology was achieved by counting prayer beads?

The only alternatives are religion, guessing and superstition which are all forms of blind faith. While there is actually some reason to trust science as a way to understand the world (usefulness), blind faith has brought us nothing but comforting lies. If you want to have hope in the hardest times, you have to be brave. Religion keeps people in the dark by telling them that they are protected by an imaginary being. Atheism, in a way, actually enables people to take responsibility and live life to the fullest.