I love the Atheism symbol, because for me it means nothing of 'free thinking', 'logical' 'fucktard' or 'genius'. It's a symbol of atoms and also science, and I also see the universe (symbolized by a solar system, the rings being planetary orbits), and my name starts with A, so that's a bonus on my own level.
Thanks to Cinjin for making it more 'sig space' friendly.