Abstract
The concept of the highest good plays a vital role in Kant’s moral theism. However, as many scholars suggest, Kant’s own texts about the very concept can be interpreted in different ways, some of which may imply that the practical postulate of God is not necessary for the realization of the highest good. In this paper, I argue, on the contrary, that within the framework of Kant’s philosophy, no matter how we interpretate the concept of the highest good, the practical postulate of God is necessary for the realization of it. The combination of virtue and happiness, let alone their perfect and exact proportionality, both for individuals and for the world as a whole, is not possible without such a postulate of God, since for Kant, virtue and happiness, as radically different elements of the highest good, are governed by different laws and true virtue can only be discerned by God. Nevertheless, this by no means entails that atheists, those who do not believe in God, cannot or should not strive for virtue and moral perfection anymore. As long as one is committed to the moral law and acts as the law commands, he can substantially contribute to realizing the highest good.