A.W. Tozer emphasizes that knowing God requires glorifying Him and being thankful, warning against the folly of exchanging God's glory for corruptible images. He highlights the darkness that ensues when people reject the truth of God, leading to moral decay and a desperate need for mercy. Tozer asserts that true knowledge of God and the ability to live righteously comes only through Jesus Christ, who is the way, the truth, and the life. The sermon calls for a deep appreciation of Christ's role in revealing God and guiding us towards a life that pleases Him.