Jacobi's polemics against philosophical theology is meant to show that neither Spinoza, nor Kant, nor Fichte nor Schelling have been able to think God as a person, that is as a free, intelligent being. In order to elucidate Jacobi's position I focus on two less well-known texts of his, viz., A Few Comments Concerning Pious Fraud (1788) and Of Divine Things and Their Revelation (1811). In the second section I situate two key philosophical theological concepts — deism and theism — against the broader context of modern philosophy. The third section analyses Jacobi's polemic against deism, followed by an examination of his positive attitude towards theism and an explanation of the reasons why he, at the end of his life, came to identify theism with deism and extended the negative meaning of the latter term to the former. In the final section, I give an outline of Jacobi's alternative idea of philosophical theology.