If you haven’t read their books already, I’d start with the Four Horsemen and Michael Shermer (I suggest beginning with Harris and Shermer and ending with Dawkins and Dennett). From there, read select Platonic dialogues (the Republic, the Apology, the Euthyphro, the Gorgias) and move to key works by Nietzsche (The Dawn, Thus Spoke Zarathustra: A Book for All and for None, Beyond Good and Evil, On The Genealogy of Morality, Twilight of the Idols, and The Antichrist).5
