Omar Khayyam (1048-1123 CE), an astronomer and mathematician famous in his own time, is best known today as the author of remarkable verses of poetry on a variety of philosophical subjects including: the meaning of life and death, the existence and nature of god, free will and predestination, and the problem of evil. A collection of his verses was translated by the nineteenth century English poet Edward FitzGerald and published in 1859 as the, Rubaiyat of Omar Khayyam, the Astronomer-Poet of Persia. The freethinker philosophy of Omar Khayyam, as expressed in his verses, was out of step with his society in the medieval Islamic world. However, his thinking was consistent with that of other freethinkers in the Middle East and may be traced to materialists in ancient Greece such as Democritus (atomism), and Epicurus (341-271 BCE). This book explores evidence that the Persian poet Omar Khayyam, and other poets in the medieval Islamic world, were influenced by the freethinkers in ancient Greece, the source of the conflict between science and religion.