Thomas Brooks emphasizes that a true Christian harbors a profound and deadly hatred for all sin, recognizing that every sin attacks God's holiness and undermines the happiness of the upright. He illustrates that sin is a universal evil that has led even the most righteous figures, like Noah, Abraham, and David, to fall. An upright heart, therefore, rises in arms against all forms of sin, viewing them as traitors to the glory of God. In contrast, an unsound heart may resist some sins while clinging to others, highlighting the need for complete rejection of sin in the life of a believer.

Thomas Brooks emphasizes that true hatred of sin goes beyond mere actions such as refraining from sin, confessing it, or fearing its consequences. He argues that genuine hatred of sin is rooted in a deep understanding of its nature and its opposition to God. Unlike hypocrites who may regret sin for its repercussions, a true believer mourns sin because it offends God and corrupts the soul. Brooks illustrates that a sincere hatred of sin is akin to hating it as one would hate hell itself, reflecting a profound spiritual integrity.