On Wednesdays, we dive into the 1,200-plus sermons we have of Pastor John’s at desiringGod.org, and pull out some choice clips from some old messages. The following clip is taken from John Piper’s sermon “Battling the Unbelief of Lust,” which he preached 25 years ago on 1 Thessalonians 4:1–8. In the sermon he explains why sexual sin is an act of unbelief. Here’s what he said.
I am trying to explode the doctrine that the battle for obedience is optional because only faith is necessary for salvation. This is very tricky, the way words are used here. Here is my response: The battle for obedience is absolutely necessary for salvation because it is the fight of faith. The battle for obedience is absolutely necessary for getting to heaven, because it is the battle against unbelief. It is the fight of faith.
There are not two battles, one to get yourself saved by a single act of faith and the other to collect rewards by works. There is only one battle. It is the one that gets you started, it is the one that gets you there, and it is the fight of faith, not works. Faith is what severs the root of covetousness, misplaced shame, anxiety, lust, envy, and six more before we are done this year. There is one warfare, and it is the warfare of faith.
Root of Lust
Let’s go to verse 5, and I will try to demonstrate for you why I think this text teaches that the root cause of lust is unbelief. Verse 5 says, “[Take a wife, or control your body,] not in the passion of lust like the Gentiles who do not know God.” Now, do you see what that implies about the root of lust? Not knowing God is the root cause of lust. Not knowing God is the root cause of lust.
“Not knowing God is the root cause of lust.”
Now what does that mean? Let’s just think about this. What kind of knowledge is he talking about? You remember how much the demons knew in the ministry of Jesus? You remember in Mark 1:24, Jesus comes into a synagogue. There is a man there with an evil spirit. Jesus is ready to cast out that evil spirit, and out of the mouth of that demon-possessed man come the words, “I know who you are — the Holy One of God.” The disciples didn’t even know that. Do you realize how much the demons know, how accurate and large their knowledge of God is on many things? And yet they seethe with lust.
So that is not the kind of knowledge that is being spoken of here. You can pack your head with theological knowledge and go straight to hell. I used to go to professional theological meetings. I remember one in Saint Louis — and Saint Louis has some pretty gross and grisly sexual streets in it. What these men who teach theology in the universities around this country did! There is no connection between mere head knowledge — mere head knowledge — and the power of godliness.
Knowledge That Liberates
So what does he mean when he says, “When you get into lust, you act like the Gentiles who don’t know God”? It is a different kind of knowledge. It is the knowledge described in 2 Corinthians 4:6, where it says, “God has shone in our hearts to give the light of the knowledge of the glory of God in the face of Jesus Christ.” It is the knowledge of God’s greatness, his grandeur, his glory, his beauty, his power, his wisdom, his justice, his goodness, his truth. It is a knowledge that humbles you and wins you and holds you.
“There is no connection between mere head knowledge and the power of godliness.”
It is the knowledge of God that is very unlike mere head knowledge. It is the knowledge that you don’t have when you say, “Ho hum,” during the hallelujah chorus. It is the knowledge that you don’t have when you grumble on the rim of the Grand Canyon at sunset: “Seeing they do not see, and hearing they do not hear” (Matthew 13:13). It is the knowledge that you have when you are like Lydia, and the Lord has just opened the heart to give heed to the glory of God in the face of Jesus Christ in the gospel (Acts 16:14). It is the knowledge that wins, holds, humbles, ravishes, enlightens, delights. It is the knowledge of faith, the assurance of things hoped for, the conviction of things not seen (Hebrews 11:1).
That is the knowledge that liberates from lust, the knowledge which is faith. It is a knowledge so real and so precious and so satisfying to your soul that when any attitude or emotion or thought or addiction threatens to diminish your capacity to have and enjoy that knowledge, you fight it as though your very life were threatened, because it is.
Do you remember 1 Peter 2:11? “Abstain from the passions of the flesh, which wage war against your soul.” Your life is at stake in the way you fight your enemy called lust.