He was recognized as a source of power and spoke and acted with authority over persons and nature. His opponents well knew the significance of his claim to forgive sins, because they believed in God. Today people who do not know God find it very difficult, sometimes impossible, to understand the notion of God's forgiveness. In a public debate with Peter Singer, when the Christian concept of moral truths was explained which, like the truths of hygiene or medicine, we can strive to know, Singer replied that such a doctrine of moral truths, which we can violate unknowingly, was heartless. It is heartless if there is no God to forgive our mistakes.
All people feel guilty sometimes, except psychopaths.
When we sin and make mistakes, we should feel guilty up to a point. Any religion that does not challenge people morally is betrayed. The love of God is reassuring, but also challenging. Forgiveness is a radical cure. God can blot out everything and not remember our sins, if we repent.