Kant does not criticize all aspects of organized religion, but he does find many tensions between moral principles and religious traditions. There are many religions, all of them influenced by their historical period, but according to Kant there is one universal moral law. Furthermore, humans can determine that moral law by relying on their own instincts. They do not need organized religion to explain it to them. Kant also believes that religious practices often conflict with or undermine moral principles. He thinks that community life, even religious community life, can foster ugly impulses toward revenge and competition. Kant believes that religious institutions often identify religious experience with the performance of certain rituals or with the acceptance of certain beliefs. This is dangerous, because individuals can simultaneously adhere to the strictest requirements of a particular church, and nurse hatred or jealousy or immoral urges.

Secondly, some religious traditions promote the idea that incantations or professions of faith endear people to God. The danger here is that people will behave morally not because it is the right thing to do, but because it is a daily chore designed to appease God. Finally, Kant objects to those religious traditions that say God's grace will save you, not your own good behavior. According to Kant, our actions have true moral worth only if we performed them independently, without God's assistance.