The philosophy of religion and the quest for spiritual truth preoccupied Albert Einstein - so much that it has been sadi one might suspect he was a disguised theologion. Nevertheless, the literature on the life and work of Einstein, extensive as it is, does not provide an adequate account of his religious conception and sentiments. Only fragmentarily known, Einstein's ideas about religion have been often distorted both by atheists and by religious groups eager to claim him as one of their own. But what exactly was Einstein's religious credo? In this book, the distinguished physicist and philosopher Max Jammer offers an answer to this question.