There are four core arguments against God's existence that have persisted since ancient times. Using these four arguments as an organizing principle, I have compared philosophers from the East vs.and West. For each argument, I've selected four philosophers who represent it. Each group contains an Eastern philosoper (Buddhist, Hindu or Confucian), a contemporary or near contemporary from the West (Pre-Socratic, Hellenistic or Roman), one from the Islamic Golden Age, and one of the New Atheist "Four Horsemen of the Apocalypse."
The four ontological arguments serve to differentiate the modern atheist movements. As I demonstrate here, the arguments from reasonable nonbelief, lack of empirical evidence, and evil are closely aligned with Freethought, Skepticism and Humanism, respectively. The argument from inconsistent revelations leads to rationalism, a metaphorical understanding of the sacred.
The argument from reasonable nonbelief is perhaps the ontological argument most closely associated with Freethought. If the existence of the gods were self-evident, everyone would believe. The burden of proof is on religion. Faith is not a virtue. Freethinkers refuse to be constricted by alien notions of the sacred. Chronologically, clockwise from top right, are Xenophanes, Gautama Buddah, Abu al-Hasan al-Ash'ari and Daniel Dennett.
Lack of empirical evidence is an argument from Skepticism. Prophesy is hearsay. Discovery trumps revelation. The incorporeal is immaterial. Clockwise from top left, are Maharishi Valmiki, Hippocrates, Muhammad ibn Zakariya al-Razi and Richard Dawkins.
The argument from evil is central to Humanism. If the gods are real, they have a lot of explaining to do. Humanism resolves the problem of evil by rejecting the idea of a divine plan or will. In an impersonal universe, there is no need to explain evil. There's no plan or divine will to implore or appease. Chronologically, clockwise from top left, are Epicurus, Hsün Tzu, Muhammad al-Warraq and Sam Harris.
The argument from inconsistent revelations often leads to rationalism, a metaphorical understanding of the sacred. Sectarian religions are mutually contradictory, but each is also internally inconsistent. All religions can't be right, and it becomes increasingly difficult to defend any of them as literally true. Chronologically, clockwise from top right, are Pliny the Elder, Wang Chong, Ibn al-Rawandi and Christopher Hitchens.
Noticing disparities within and among religions can lead the believer to rationalism, a metaphorical understanding of the sacred, as untenable beliefs have to be reconciled with contradictions. Rationalism makes it possible for atheists to maintain their cultural religious affiliations. Unitarian Universalism and Humanistic Judaism are rationalist religions. They are inconsistent with (Secular) Humanism because they are obscurantist.
Remarkable similarities can be found in the parallel trajectories of doubt in the East and West. Eastern religions are generally more rationalistic, but doubt does not arise without a doctrine to reject. Doubt follows a remarkably similar trajectory in Eastern and Western traditions. We can infer the supernatural beliefs of the people from the cautions issued by their philosophers.
Each of the four ontological arguments helps to differentiate the various modern atheist movements. The arguments from reasonable nonbelief, lack of empirical evidence, evil are essentially Freethought, Skeptical, and Humanist arguments, respectively, while rationalism follows form the argument from inconsistent revelations.
Each of the Four Horsemen lends a unique strength to the argument allocated to him here. Dennett has put his own stamp on the Freethought argument by "breaking the spell" that insulates religion from criticism. As a biologist, Dawkins is especially adept at the Skeptical argument. Hitchens could evicerate inconsistent revelations with relish. Harris' work on moral intuition make a compelling case for Humanism.
Although it is well known that the philosophers of the Islamic Golden Age studied the ancients, doubt is organic and will emerge spontaneously and independently. It arose according to a remarkably similar trajectory in the East and West despite geography. Belief is ubiquitous, but so is doubt. The difference is that the particulars of belief are taught.