Richard Dawkins, Dan Dennett, Christopher Hitchens and Sam Harris have taken up the collective title of the Four Horsemen as a kind of rebuff or joke. They are openly atheistic and are working in the academic and public fields for the humanist cause. I find myself dipping into their fonts of knowledge and opinion from time to time.
This is a (continually updated) list of my articles focused on their contributions:
[note - haven't done much yet on Richard Dawkins]