Thomas Brooks emphasizes that all Christians harbor secret sins, often unknown even to themselves. He reflects on the nature of human error, asserting that no one, regardless of their holiness or wisdom, can fully comprehend their own sins. Brooks highlights various forms of secret sins, including pride, hypocrisy, and unbelief, suggesting that if these were visible, it would cause profound shame. He urges believers to seek God's cleansing from these hidden faults, echoing the plea found in Psalm 19:12.

Thomas Brooks emphasizes the struggle against secret sins and inward pollutions that only God and the individual can see. He contrasts the hypocrite, who battles obvious sins, with the sincere Christian who mourns over hidden corruptions. Brooks highlights the importance of recognizing and combating these inner sins before they lead to greater danger, urging believers to seek God's help in stifling the first motions of sin. The sermon calls for a deep introspection and reliance on divine power to cleanse the heart from these secret faults.

Thomas Brooks emphasizes the importance of recognizing and detesting vain thoughts, which are often hidden from others but significant in the eyes of God. He illustrates that a holy man is aware of the dangers of secret sins, understanding that they require repentance just as openly visible sins do. Brooks points out that these hidden sins can be more perilous and that they grieve the Holy Spirit, urging believers to confront and humble themselves regarding their inner struggles. He draws on the example of Hezekiah, who humbled himself for the pride of his heart, highlighting the need for self-examination and accountability in one's spiritual life.