The sermon centers on the peril of basing one's faith on subjective feelings or thoughts, warning that trusting in the heart—our emotions, intuitions, or personal convictions—is spiritually foolish, as Scripture declares the heart to be deceitful and desperately wicked. Drawing from Proverbs 28:26, it emphasizes that true wisdom and salvation come not from internal feelings but from submitting to the objective, unchanging truth of God's Word, which is the only reliable standard for evaluating the genuineness of faith. The preacher argues that feelings, though powerful, are unreliable because they are shaped by sin, influenced by deception, and subject to change, and thus cannot be the foundation of assurance in one's salvation. Instead, genuine faith must be tested by Scripture, evidenced in a life marked by obedience, love, and submission to Christ's lordship, not merely by emotional experiences or past professions. Ultimately, the sermon calls believers to humility, self-examination, and reliance on God's Word and godly counsel to discern whether their faith is real or merely self-deceived.