The Quran is a sacred book with profound, and familiar, Old and New Testament resonances. And the message it promulgated, Islam, came of age during an extraordinarily rich era of interaction among monotheists. Jews, Christians, and Muslims not only worshipped the same God, but shared aspirations, operated in the same social and economic environment, and sometimes lived side by side, indistinguishable by language, costume, or manners. Today, of course, little of this commonality is apparent, and Islam is poorly understood by most non-Muslims. Entering Islam through the same biblical door Muhammad did, this book introduces readers with Christian or Jewish backgrounds to one of the world's largest, most active, and - in the West - least understood religions.