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 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.