The moral agent’s response to radical evil is a moral conversion or change of heart, inverting the order of incentives in the maxim of evil and giving priority to the moral incentive. Kant regards the moral incentive as distinctive, different from all others. Kant often refers to it as “duty,” but in the reception of Kant, this is often misunderstood as unemotional coldness of heart. Giving priority to the moral incentive for Kant is rather “goodness of heart,” involving caring for others and a proper balance between love and respect for them. Goodness of heart is also linked to virtuous nonmoral incentives. Also frequently misunderstood is how Kant understands acting from an incentive. Acting from an incentive, whether the moral one or a nonmoral one, is not a property of individual acts. Rather, it is a property of an agent’s disposition or character. Virtus noumenon is the character of a person who has undergone the change of heart. This manifests itself only as virtus phaenomenon, involving empirical incentives and habitual behavior, which may be a mere appearance of virtue but is also the only possible manifestation of true virtue. “Acting from duty” means something different in the Groundwork from what it means in later works, where it is related to the morality (not the mere legality) of actions and to the duty to act from duty. The change of heart is not a datable event in a person’s life but depends on the striving for moral progress, which can be known only by God who sees the entire course of a person’s life.

Kant’s moral argument for faith in God aims not at converting unbelievers but at offering those who believe a reason for principled assent to the existence of God on moral grounds. It is based on a rational connection between purposive action and assent that applies not only to religious belief but to many other purposes as well, such as what Royce called “loyalty to a lost cause.” The argument in the Critique of Pure Reason differs significantly from its presentation in later works. Kantian moral faith is in tension with Cliffordian evidentialism but not inconsistent with it, and the two together constitute the doxastic virtue lying between the twin vices of uncritical credulity and stubborn incredulity; together they enable us to avoid the complacencies of both despairing resignation and overconfidence.

Kant’s thesis that there is in human nature an innate, universal, inextirpable, and radical propensity to evil belongs to his attempt to choose fragments of (Christian) revelation and see if they cannot be seen to lead back to the religion of pure reason. Though Kant regards this thesis as unproven, he offers it as an interpretation of the Christian doctrine of original sin that can be used in moral discipline, though not in moral dogmatics. To understand Kant’s concept of evil, we must understand his concept of freedom and disentangle it from incomprehensible metaphysical speculations with which it has often been associated in the literature. Kant’s concept of moral evil is extremely abstract, consisting in the choice of some nonmoral incentive over the moral incentive. Evil can never be made entirely intelligible because evil is action, hence done for reasons, but there can never be a sufficient or decisive reason for doing it because the moral incentive is rationally prior to all nonmoral incentives. But Kant thinks evil can be made intelligible to an extent by seeing it as part of nature’s purposiveness in developing human species predispositions in the social condition.

Moral progress is understood religiously as the hope that despite our having begun from evil, we can make ourselves well-pleasing to God. This hope rests on the hope that we have undergone the change of heart, which is symbolized in rational religion as faith in the Son of God or the ideal of humanity well-pleasing to God. Understanding this requires further investigation of the role of symbols and analogy in religion, which was discussed in Chapter 1. The hope to become well-pleasing to God is threatened by three difficulties, two of them based on doubts that we have undergone the change of heart or can sustain it in our lives, and the third (and greatest) based on the fact that we began from evil and have incurred a guilt we cannot wipe out. The hope to become well-pleasing to God therefore depends on God’s decree of grace. We can understand this in terms of God’s forgiveness – not the forgiveness of a debt but God’s willingness to accept our change of heart as an atonement making us morally receptive to his freely given mercy.

Kant’s concept of religion is recognizing all duties as divine commands. The concept of God employed in religion is an analogical or symbolic concept. Kant’s relation to Christianity was characterized by a tension between Pietism and Enlightenment rationalism. Religion within the Boundaries of Mere Reason aims to test a hypothesis: that there is such a thing as a religion of pure reason and that its relation to revealed (Christian) religion need not be one of conflict but can and should be harmonious. The publication of Kant’s book involved conflict with the Prussian authorities, in which Kant adopted a position of principled obedience while resisting unjust repression and conforming to the rule of law.

Kant holds that the origin of our propensity to evil arises in connection with our unsociable sociability. The effective response to it, therefore, must also be social. We must leave the ethical state of nature and join with others in voluntary ethical community, where our shared ends, conceived as the highest good, under the legislation of a divine lawgiver will promote moral progress among human beings. The existing communities of this kind are churches and ecclesiastical faiths, which fall short of their religious vocation but can and should be reformed so as to live up to it. The relation of rational religion to revealed religion is therefore intended by Kant to be dynamic, with the interpretation of revealed religion enriching rational religion and the reform of revealed religion bringing rational and revealed religion into closer harmony, leading gradually toward the founding of the Kingdom of God on earth.

Justifying grace is for Kant the way religion symbolizes, in terms of our relation to God, our hope to overcome the propensity to evil through the change of heart. Divine forgiveness does not abolish or transcend morality but occurs in accordance with morality. The Son of God symbolizes as vicarious atonement our moral receptivity to God’s mercy. The sacrifice of Jesus Christ on the cross is the way Christianity symbolizes it in revealed religion. For Kant rational religion includes faith in God’s justifying grace. It does not include prevenient or sanctifying grace but does not exclude these either. They are religiously acceptable parts of revealed Christianity, but their reality and our need for them lie beyond what pure reason can know. Some critics claim that Kant’s account of divine grace is inconsistent with itself. But closer examination shows that it is self-consistent, and for Kant rational religion is even consistent with Augustinianism about grace, while neither affirming nor denying it.

Kant is critical of many of the practices of Christianity in his time. But when we appreciate the dynamic relation between rational and revealed religion as Kant conceives them, the apparent opposition becomes more questionable and raises more questions than it answers. Kant’s project in the Religion bears important affinities with the religious philosophy of Moses Mendelssohn. Mendelssohn’s philosophy of church and state and their relation involve a number of radical proposals expressive of Enlightenment religious consciousness. Mendelssohn’s concept of enlightened Judaism bears interesting comparison to Kant’s enlightened reflections on Christianity. Mendelssohn defends a form of evidentialism even more radical that Clifford’s. He also defends a conception of the freedom of religious conscience that inspires Kant’s treatment of that topic in part four of the Religion. Conscience is an important theme in Kant’s moral philosophy, which has special application to religious conscience and the freedom of conscience Kant and Mendelssohn both defend.

Kant’s reflections on religion represent a road not taken in the modern world – a way of reconciling religious faith and religious symbols with a modern scientific and Enlightenment culture. We may question Kant’s hope for a universal world faith in light of Mendelssohn’s defense of separate churches and religious ways of life. But the world would be a better place if the aspirations of Kant and Mendelssohn had shaped the relation of religion to culture in the past two hundred years.