The statement "The human being is evil" cannot mean anything else than that he is conscious of the moral law and yet has incorporated into his maxim the (occasional) deviation from it. (6:32)
In this brief passage, Kant introduces two ideas that animate all of his thinking about religion and morality. First, he says that human beings are evil when they intentionally decide to act against their better judgment. Second, he says that immoral action is not simply a matter of acting on immoral impulses. Humans act according to maxims, or principles of action, and humans are evil when they knowingly create a maxim that allows occasional bad behavior. Evil involves intentionally formulating a principle that sanctions illicit actions. Evil, therefore, is not simply an action, it is a premeditated action performed in accordance with a set of principles.
The restoration of the original predisposition to good in us is not therefore the acquisition of a lost incentive for the good, since we were never able to lose the incentive that consists in respect for the moral law The restoration is therefore only the recovery of the purity of the law, as the supreme ground of all our maxims, according to which the law itself is to be incorporated into the power of choice, not merely bound to other incentives, nor indeed subordinated to them as conditions, but rather in its full purity, as the self-sufficient incentive of that power. (6:46)
Kant believes that we can never truly lose our predisposition to do what is right. We can, however, place our illicit, immoral desires ahead of our more respectable moral inclinations. In this quotation, Kant says that true moral behavior consists of subordinating our illicit, immoral desires to our respect for the moral law. We will always have self-serving, immoral impulses and desires, but as long as we quash them, we are behaving morally. Kant urges us to think of moral law as the ultimate ruler of our decisions, not as one consideration among many.
To become a morally good human being it is not enough simply to let the germ of the good which lies in our species develop unhindered; there is an active and opposing cause of evil which is also to be combated. (6:57)
This comment shows one of the similarities between Kant's religious thought and Christianity. Kant believes that evil behavior does not simply result from a failure to do what is virtuous or morally sound. It results, rather, from an active, immoral predisposition in us. We have a "germ of good," but we also have a germ of evil that we must work to combat. Kant says that good behavior will not develop naturally if we simply relax; it will only flourish if we counteract our tendency toward evil behavior.
There is absolutely no salvation for human beings except in the innermost adoption of genuine moral principles in their disposition, and that to interfere with this adoption is surely not the so often blamed sensibility but a certain self-incurred perversity, or as we might otherwise also call this wickedness, fraud. This is a corruption that lies in all human beings and cannot be overcome except through the idea of the moral good in its absolute purity. (6:83)
Here Kant explains his idea that we must actively combat evil in order to become truly good. He says we must reform our own dispositions. Relying on God or Jesus will not help us out of a moral slump. Good, for Kant, is not an abstract that exists outside humans, but an inner resource that we all possess. Therefore, a refusal to be good is a refusal to draw on our own inner resources. Badness is not the fault of a defective personality, Kant says, but "self-incurred perversity," for it is perverse to turn your back on your own capacity for goodness. While we have the capacity for good, however, we also have the capacity for evil. We must draw on our goodness, but we must also believe that "absolute purity" exists, and model ourselves on that.
The basis for the transition to the new order of things must lie in the principle of the pure religion of reason, as a revelation permanently taking place within all human beings, and this basis, once grasped after mature reflection, will be carried into effect, inasmuch as it is to be a human work, through gradual reform. (6:122)
Kant says that adoption of his moral reason will happen gradually, and root itself into humans permanently. Once humans understand the principle behind "pure religion," and give the principle "mature reflection," they will begin to adopt it. Kant does not expect that his theories will take hold immediately. He understands that because this reform will be "a human work," it will necessarily happen through "gradual reform."