Elisha ben Abuyah became a skeptic as a consequence of seeing a person meet with a fatal accident at the very moment when he was fulfilling the two divine commandments for the observance of which Scripture holds out the promise of a long life. Skepticism in the Medieval era The rationalistic era of Islam produced skeptics among the Jews of the time of Saadia, such as was Ḥiwi al-Balkhi, whose criticism tended to undermine the belief in revelation. The Emunot ve-Deot was written by Saadia, as he says in the preface, because of the many doubters who were to be convinced of the truth; and Maimonides, in the introduction to his Moreh, states that he wrote that work as a guide for those perplexed by doubt. With all these Jewish thinkers doubt is not a sin, but an error that may reveal the pathway to the higher philosophical truth. A remarkable type of skeptic was produced by the sixteenth century in Uriel Acosta, who, amidst a life of restless searching after truth, denied the immortality of the soul and the divine revelation. His excommunication by the Amsterdam authorities was inspired by fear of the Christian Church rather than by traditional practice. Another such was Leon of Modena, who, complaining that "the thinker is tortured by doubt, whereas the blind believer enjoys peace of mind, and bliss in the world to come" (see Ari Nohem, quoted by H. Grätz, Gesch. 3d ed., x. 130), arrived through skepticism at a liberal interpretation of traditional Judaism (see S. Stern, Der Kampf des Rabbiners Gegen den Talmud im xviii. Jahrhundert, 1902). Skepticism in the Early Modern and Modern Period Strictly speaking, Jewish engagement with atheism (i.e. disbelief in God’s existence) can scarcely be found before the modern period, unless one expands the definition to include biblical condemnations of practical atheism (i.e. non-observance), and Jewish attraction to ancient world beliefs that might be said to have challenged the idea of Jewish monotheism. Of course, there were also debates about the existence of others’ gods (e.g. disbelief in the official gods of the Classical world, or disbelief in the triune God of Christianity), which generated condemnations of Jewish atheism. Likewise, serious Jewish encounters with the Greek sources of philosophical scepticism (i.e. disbelief that a true knowledge of things is attainable by humans) are rare until thinkers like Simone Luzzatto in the early-modern period, although a weaker