In Good Without God: What a Billion Nonreligious People Do Believe, Greg Epstein (2007) presented Darwin, Marx, Nietzsche and Freud as the "Four Horsemen of the Apocalypse" of their time. Massimo Pigliucci characterized the Pre-Socratics as a "intellectually wild" bunch in his (2010) book Nonsense on Stilts How to Tell Science from Bunk. Here I present Four Horsemen of the Islamic Golden Age.
The argument from evil- If the gods are real, they have a lot of explaining to do. Chance rules the universe.
The argument from inconsistent revelations- All religions can't be right, so they're probably all wrong. This is also known as cosmopolitan doubt.
Cultural relativists who are squeamish about imposing European values on Islam really should consider that Islamic Golden Age philosophers revived the campaign against religious authority well ahead of the Enlightenment.