Spinoza has been called both a'God-intoxicated man'and an atheist, both a pioneer of secular Judaism and a bitter critic of religion. This study brings together his fundamental philosophical thinking with his conclusions about God and religion. Spinoza was born a Jew but chose to live outside any religious community. He was deeply engaged both in traditional Hebrew learning and in contemporary physical science. He identified God with nature or substance: a theme which runs through his work, enabling him to naturalise religion but-equally important-to divinise nature. He emerges not as a rationalist precursor of the Enlightenment but as a thinker of the highest importance in his own right, both in philosophy and in religion. This book is the fullest study in English for many years on the role of God in Spinoza's philosophy.