Kant disagrees with some tenets of Christianity and agrees with others. He rejects the Christian doctrines of origin sin and salvation. Yet he also believes that Christianity is superior to other monotheistic religions, primarily because it encourages the development of a truly ethical community and a commitment to internal moral principles. In short, Kant sees the seeds of his own moral religion in Christianity.
According to Kant, a comparison between Judaism and Christianity shows how revolutionary the Christian faith can be. In his view, Judaism is a public religion, which means that its core principles are more akin to public laws than to internal moral principles. In fact, all of Judaism's "commands are of the kind which even a political state can uphold and lay down as coercive laws, since they deal only with external actions" (6:126). Additionally, Kant says, Judaism has restricted its membership to an exclusive group of people, thereby thwarting any possibility of developing into a universal church whose laws would apply to all people.
For Kant, Christianity is best understood not as a continuation of Judaism, but as the beginning of something new. In lieu of public laws governing moral behavior, Christianity requires internal laws that govern what is morally right. Kant lauds Christianity's inclusiveness, passing off such horrors as the Crusades and the persecution of the Jews as anomalies, unfortunate but isolated departures from the core message of this dominant world religion.
Kant goes on to explain that all religious faiths involve something holy that people can comprehend at least partially. Kant says that in worthwhile religions, this holy quality is usually embodied in a moral ruler of the world, a deity who has the final word on all moral questions and concerns. Some faiths articulate the relationship between the moral ruler and humanity better than others. For Kant, true religions believe in a God who is as a morally holy lawgiver, a benevolent ruler, and a just judge and administrator of his laws.
Just as Kant understands Jesus as the ideal of perfect morality, he understands God as an ideal. We do not literally owe allegiance to a holy lawgiver or an actual judge. Rather, we should interpret God allegorically, and let God inspire us to become holy, to counteract our natural tendency toward immoral conduct, and to urgently reform our own behavior. Kant believes that the moral wisdom in Christianity can be gleaned only from an allegorical understanding of Christianity.
Kant sees Christianity as the historical expression of truth that lies dormant in the human heart, waiting to be unearthed through conscientious reflection. If we do not discover this truth, we are responsible, for we did not search our own hearts long enough to uncover it.