 Kant’s moral argument for belief in God in the Critique of Practical Reason may be summarized as follows. Kant holds that virtue and happiness are not just combined but necessarily combined in the idea of the highest good, because only possessing virtue makes one worthy of happiness – a claim that Kant seems to regard as part of the content of the moral law (4:393; 5:110, 124). But we can represent virtue and happiness as necessarily combined only by representing virtue as the efficient cause of happiness. This means that we must represent the highest good not simply as a state of affairs in which everyone is both happy and virtuous, but rather as one in which everyone is happy because they are virtuous (5:113–114, 124). However, it is beyond the power of human beings, both individually and collectively, to guarantee that happiness results from virtue, and we do not know any law of nature that guarantees this either. Therefore, we must conclude that the highest good is impossible, unless we postulate “the existence of a cause of nature, distinct from nature, which contains the ground of this connection, namely the exact correspondence of happiness with morality” (5:125). This cause of nature would have to be God since it must have both understanding and will. Kant probably does not conceive of God as the efficient cause of a happiness that is rewarded in a future life to those who are virtuous in this one. Rather, his view is probably that we represent our endless progress toward holiness, beginning with this life and extending into infinity, as the efficient cause of our happiness, which likewise begins in this life and extends to a future one, in accordance with teleological laws that God authors and causes to harmonize with efficient causes in nature (A809–812/B837–840; 5:127–131, 447–450).