Thomas Brooks emphasizes that a sincere willingness to part with every sin is a clear indication of saving grace. He asserts that true integrity and saving faith are demonstrated by a person's commitment to forsake all sins, including their 'darling' sins. Brooks explains that it requires divine power and grace to overcome these beloved sins, and that a godly person does not engage in a habitual or willful practice of sin. The assurance of being upright before God is rooted in the active choice to keep oneself from sin. Ultimately, the sermon calls believers to reflect on their relationship with sin and their commitment to holiness.

A sincere willingness to part with every sin, and to mortify every sin—is a sure sign of saving grace. When a man is sincerely willing to leave every sin, and to indulge himself in none, no, not even his darling sin—it is a most certain sign of his integrity and saving faith. "I am upright before God; I have kept myself from sin." Psalm 18:23 "I am upright before God." Oh! but how do you know that? How do you prove that? How are you assured of that? Why, by this—that "I have kept myself from sin." Doubtless there is as much of the power of God required, and as much strength of grace required, and as much of the presence and assistance of the Spirit required—to work a man off from his bosom sins, from his darling sins, from his beloved sins. A conquest here clearly speaks out uprightness of heart before God. The godly man . . . does not give himself over to a voluntary serving of sin; does not make a trade of sin; does not allow of himself in any settled course of sin; does not indulge, connive or wink at any known sin; does not sin as wicked men sin—who sin studiously, resolutely, ardently, delightfully, customarily, willfully. The ungodly sin with their whole will, and with the full consent and sway of their souls.