Winning the Battle Within

Trinity 14| Pastor James Preus| Galatians 5:15-23| Trinity Lutheran Church| September 6, 2026

Every Christian knows that our greatest enemy is Satan. He is the archenemy of Christ and His Church. We pray against Satan in every petition of the Lord’s Prayer. Scripture says that the devil prowls around like a roaring lion, seeking someone to devour (1 Peter 5:8). He desires our total destruction and damnation. But who do you think is your next greatest enemy? Hardly anybody gets through life without accumulating enemies. Even if you try to be at peace with everyone, some people just want to fight. Or their evil is so repugnant, that we have no choice but to oppose them. So, who do you think, after Satan, is your greatest enemy?

That enemy dwells within. It is your own sinful flesh, also known as your old Adam. Even in Christians, this old Adam continues to sabotage our efforts to live a godly life. St. Paul describes it as a war within us, “The desires of the flesh are against the Spirit, and the desires of the Spirit are against the flesh, for these are opposed to each other, to keep you from doing the things you want to do.” (Galatians 5:17) Paul writes of this inner conflict in Romans chapter seven as well, “For I know that nothing good dwells in me, that is, in my flesh. For I have the desire to do what is right, but not the ability to carry it out.” (vs. 18) Jesus teaches His disciple Peter this when He says, “The spirit indeed is willing, but the flesh is weak.” (Matthew 26:41) And our Lord says in Matthew 15, “For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false witness, slander. These are what defile a person.” (vs. 19-20a)

So, we Christians should recognize how closely this enemy clings to us. Yet, you should also recognize how much damage this enemy can do to you. There may be certain persons who aggravate you, whom you count as your enemies. But what damage can they do to you compared to the damage this inner enemy can do to you? No one can destroy your career, cost you more money, damage your marriage or your relationship with your children, or soil your reputation like your own sinful flesh. If someone slanders my name, the truth may vindicate me. But if I obey the passions of my flesh and indulge in sexual immorality, fits of anger, or drunkenness, then I cause more damage to myself than my greatest opponent ever could. And you should take note of this if you are prone to complain about others or be suspicious of their wicked motives, and rather do as the saints in the Bible do, and complain to God of your own sinful flesh and be suspicious of your own sinful motives. They will ruin you much faster and more thoroughly than anyone else you have ever complained about.

And this ruin goes beyond this life. St. Paul writes, “Now the works of the flesh are evident: sexual immorality (that is, fornication, the Greek word is porneia), impurity, sensuality, idolatry, sorcery, enmity, strife, jealously, fits of anger, rivalries, dissensions, divisions, envy, drunkenness, orgies, and things like these. I warn you, as I warned you before, that those who do such things will not inherit the kingdom of God.” (vss. 19-21) What does it mean that they will not inherit the kingdom of God? It means that they will be condemned to hell, as Revelation 21 states, “But as for the cowardly, the faithless, the detestable, as for murderers, the sexually immoral, sorcerers, idolaters, and all liars, their portion will be in the lake that burns with fire and sulfur, which is the second death.” (vs. 8)

It is true that everyone sins, even Christians. If we say we have no sin, we deceive ourselves and the truth is not in us (1 John 1:8). However, it is also true that those who persist in sin without repenting have abandoned the faith. St. John writes, “Whoever makes a practice of sinning is of the devil, for the devil has been sinning from the beginning. The reason the Son of God appeared was to destroy the works of the devil. No one born of God makes a practice of sinning, for God’s seed abides in him; and he cannot keep on sinning, because he has been born of God.” (1 John 3:8-9) Saving faith is not mere historical knowledge. A person can know the Nicene Creed by memory, but that does not make him a Christian. Rather, saving faith trusts in Christ from the heart, and so, seeks to resist sin.

So, this is no small matter. If you permit your old sinful flesh to get the better hand and to rule over you, you will lose your inheritance. The Holy Spirit will depart from you. This is why St. Paul exhorts us, saying, “Flee from sexual immorality.” (1 Cor. 6:18), and “Do not get drunk with wine, for that is debauchery, but be filled with the Holy Spirit.” (Ephesians 5:8) And why St. James writes, “the anger of man does not produce the righteousness of God.” (James 1:20) Everyone feels sin. This is why our Lord teaches us to pray every day, “Forgive us our trespasses.” And though Christians try, they cannot live without sin. You cannot keep the birds from flying over your head, but you must keep them from building a nest in your hair! If sin takes control of you, so that you obey it and persist in it, then you can no longer call yourself a Christian. Then you have denied Christ and forfeited your inheritance. By becoming slaves of the passions of the flesh, many have made shipwreck their faith (1 Timothy 1:19), because they cannot hold the faith with a good conscience.

And so, this is not a secondary thing. We cannot sit out this battle, but we must daily wage war against our sinful flesh, so that it does not make us obey its passions. So, how are we going to win this battle? The works of the flesh St. Paul lists all break the Ten Commandments. And so, many conclude that we defeat the old sinful flesh through works of the Law. But that is not true! We cannot win our internal battle with the Law! Why? Because the Law does not give us the Holy Spirit, but only tells our sinful flesh what to do. St. Paul writes earlier in Galatians 3, “Let me ask you only this. Did you receive the Spirit by works of the law or by hearing with faith? Are you so foolish? Having begun by the Spirit, are you now being perfected by the flesh?” The Law does not produce good works in us. Instead, it only magnifies our sin, as Paul writes in Romans 5, “Now the law came in to increase the trespass,” and in Romans 7, “I was once alive apart from the law, but when the commandment came, sin came alive and I died.”

It is not that the Law causes us to sin, but rather, it exposes our sin. The more we focus on the Law, the more we become aware that we have broken it. And so, the Law is very good at condemning the flesh, but it does not give you the power at all to do what is right. Only the Holy Spirit does that. And you receive the Holy Spirit through the Word of Christ, that is, through the Gospel. The Holy Spirit comes to us through the Good News that Christ Jesus has overcome our sinful flesh, wiped away our sin, and grants us forgiveness and sanctification through His Holy Spirit, as St. Paul writes in Romans 8, “For God has done what the law, weakened by the flesh, could not do. By sending his own Son in the likeness of sinful flesh and for sin, He condemned sin in the flesh, in order that the righteous requirement of the law might be fulfilled in us, who walk not according to the flesh but according to the Spirit.” (vss. 3-4)

This is why Paul says, “Walk by the Spirit.” (Gal. 5:16) And “If you are led by the Spirit, you are not under the law.” (Gal. 5:18) To walk by the Spirit means to walk through faith in Jesus Christ. Jesus has fulfilled the Law in our place and suffered for our sins in His flesh. This is why Scripture declares, “There is therefore now no condemnation for those who are in Christ Jesus.” (Romans 8:1) What the Law failed to accomplish, because of the weakness of our sinful flesh, Jesus accomplished through His perfect obedience, death, and resurrection. The Holy Spirit gives us Jesus’ victory to be received through faith. We possess this victory both passively and actively. Passively, we hold Jesus’ victory through faith, so that, although we still sin, God does not count our sin against us, but forgive us, and credits Christ’s righteousness as our own. And actively, this victory manifests itself through us. The righteous requirement of the law is fulfilled in us, because the Spirit is at work in us.

This manifests itself through the fruits of the Spirit, which are love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control. St. Paul says, against such things there is no law. St. Paul purposefully calls these fruits of the Spirit, not works of the Spirit. These are not works done under the compulsion and threats of the Law, but they are fruits produced spontaneously through the Holy Spirit who dwells in believers. These are fruits produced willingly by the new self, created after the image of Christ. And we see this as we examine these fruits. Love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control. Whom do these describe? They describe Christ, who out of love for His Father and for us and for the joy set before Him endured the cross and laid down His life to save us, thus securing peace with God for us. He is so kind and good to us, that He patiently endures our burdens and takes them as His own. His faithfulness gives our faith something to depend on. He gently guides His little lambs and goes after those who have strayed. Through self-control, He endured every temptation, so that He could make a perfect sacrifice for our sins.

Through faith in Christ, the Holy Spirit transforms us to be like Christ. He does this by forgiving our sins through Baptism, through the preaching of the Word, through the Absolution, and through the Sacrament of Christ’s body and blood. This is how God gives us Christ’s forgiveness and righteousness, so that we may receive them through faith. This is how God transforms us inwardly, so that we may overcome our sinful flesh.

But people do not accept this. How can grace, mercy, and forgiveness overcome sinful impulses? Wouldn’t that make them worse? Don’t we need the Law to bludgeon these sinful impulses away? We do use the Law to identify this indwelling sin, so that we daily repent. But the Law cannot overcome the impulse of sin. Only Christ can do that. And so, we put off the old self with its sinful desires by daily repenting of our sins, renouncing the works of the flesh, and we walk in newness of life according to the new self which is given to us in Baptism through faith in Christ Jesus. We die to sin every day, so that we may live to Christ. “There is therefore now no condemnation to those who are in Christ Jesus.” (Romans 8:1) It is through faith in this fact that we overcome the flesh, for as St. Paul writes in 1 Corinthians 1, “And because of Him you are in Christ Jesus, who became to us wisdom from God, righteousness and sanctification and redemption, ³¹ so that, as it is written, “Let the one who boasts, boast in the Lord.” (vss. 30-31) It is through faith in Christ Jesus, who has defeated our greatest enemy that we also overcome the enemy within. Amen.