The thesis is that much of Spinoza's philosophy was conceived with the express purpose of rebutting a claim about the limitations of philosophy made by some of his contemporaries. They held that philosophy is intrinsically incapable of revealing anything of any relevance to theology, or in fact to any study of direct practical relevance to human life. Spinoza did not. He believed that philosophy reveals the true nature of God, and that God is nothing like what the majority of theologians, or indeed of religious believers in general, think he is. The practical implications of this change in the concept of God were profound and radical. As Douglas shows, many of Spinoza's theories were directed towards showing how the separation his opponents endeavoured to maintain between philosophical and non-philosophical (particularly theological) thought was logically untenable.