Sin is not an action, but rather a condition, a state of mind. People often think that their sinfulness increases every time they commit a wrongful act. The truth is far worse: sinfulness increases every moment that a person fails to take action to pursue faith and overcome his or her sinful state.
Sections (a), (b), and (c) describe particular ways in which people may intensify their sin by failing to take action against it. Section (a) describes the sin of despairing over one's sinfulness. In this sin, an individual recognizes that he or she is living in sin but adopts a mindset of self-pity rather than pursuing faith. Such a mindset involves an intensification of sin because the individual has recognized that he or she is sinful and yet has chosen to dwell on the sin rather than act to alleviate it.
Section (b) describes the sin of refusing to believe in the forgiveness of sins. At first glance, this refusal might seem to be a mark of sophistication, a sign that the individual is wrestling with religious truths. It is in fact a mark of the gravest sin. Christianity's fundamental command is that human beings must believe in Christ and in the forgiveness of sins. It is a sin to reject this teaching.
This sin was not possible for pre-Christians, who were aware only of specific crimes and wrongs. Unlike earlier religions, Christianity stipulates that individuals must maintain a relationship with God through which they pursue forgiveness for their sins. However virtuous they may appear, people who seek comfort in doing as others do fail to lead the true Christian life of private belief and introspection.
Section (c) describes the highest intensification of sin, the sin of rejecting Christ's teachings. Christianity teaches that human beings must strive to maintain an individual relationship with God, despite the vast differences between God and human beings. Those who choose to remain undecided about the truth of Christianity commit sin because they violate the Christian imperative that all individuals shall believe in Christ. Those who want to believe in Christ but feel unable to believe in his paradoxical teachings are also in sin. The most intense sin, however, is the sin of those who willfully refuse even to try to believe in Christ.
The final paragraph offers something of a summary of the book's main points. The opposite of sin is faith. Those who are in sin are in despair. Faith is the condition of establishing a relationship with God that eliminates despair and sin.