Though Jews are assumed to have a special affinity for atheism, a careful glance at the historical record suggests this hypothesis has yet to be verified. Basic terms in the languages of Judaism that refer to atheists are exceedingly difficult to pinpoint and translate. Instead, the historical sources conspire to severely diminish our ability to conclusively identify Jewish non-believers in the pre-modern and early modern periods. Christian sources pertaining to atheism, although equally difficult to decipher, are far more copious and detailed. At present, it seems safest to say that the first class of self-conscious, socially mobilized Jewish atheists emerged in the post-Marxist ferment of the late nineteenth century and crested in the middle of the twentieth.