John Gill emphasizes the importance of aligning one's actions with their professed knowledge of God, warning against the hypocrisy of claiming to know Him while disregarding His commandments. He critiques those who, like the Gnostics, boast of spiritual enlightenment yet fail to demonstrate obedience, revealing their true ignorance. Gill asserts that true knowledge of God is evidenced by a life of obedience, and without this, one is a liar and lacks the truth of the Gospel in their heart.