Kant, Immanuel (1724–1804)

The philosopher Immanuel Kant, born in 1724, in the Prussian city of Königsberg, is recognized as one of the most important figures of the 16th-century Enlightenment. In reaction to the ritual and disciplined pietistic atmosphere that prevailed where he grew up, Kant developed a theory of duty based on human autonomy.

According to Kant, human will is fair—a good will—only if actions are motivated by duty itself. The idea of God is necessary from the practical point of view—as the idea of the supreme moral ruler of the world and the source of moral norms. Thus, the fundamental reason for religion is practical because, over and above particular doctrines, its ultimate function is to guide individual moral life and lead humanity to the moral destiny of peace. The establishment of an ethical commonwealth, the way to universal and eternal peace, is only possible as the organization of the people of God under laws of virtue, as an invisible church that gathers every just person in the world. The visible church must evidence that invisible one as the presence of God's moral kingdom on earth through its unity, purity, freedom, and immutability.

Only a pure rational faith makes it possible for the universal visible church to practice the religion of reason, natural religion; but this pure moral religion needs the help of a religion of God's service and worship to attract believers from a historical faith to the rational faith. Any true historical religion must perform this function for the human species.

For Kant, there are three essential questions to assess what ought to be done in human life: (1) the existence of God, (2) the possibility of a future life, and (3) the freedom of human will. Paradoxically, these important questions cannot be answered by human reason because they are not a subject of knowledge and all attempts to explain them are only speculation. The affirmation of the existence of God is a regulative principle accepted by moral faith, and people must act as if God and future life really exist, because, just like freedom, these two statements are postulates of practical reason. If they do not exist, moral law is just a fiction.

Kant interpreted the Bible from a moral point of view and subordinated the message of the sacred texts to practical reason, from where the sense of the biblical texts comes. In 1794, after the publication of Religion Within the Boundaries of Mere Reason, Kant was accused by King Friedrich Wilhelm II of changing the original sense of some basic faith elements and also of altering the biblical message. Kant rejected the accusation but did not publish any text on religion until the king's death in 1797.

Kant died in 1804 in Königsberg. His writings on religion were to have a profound influence on the secularization project of modernity.