Let not sin therefore reign in your mortal body, to make you obey its passions. Do not present your members to sin as instruments for unrighteousness, but present yourselves to God as those who have been brought from death to life, and your members to God as instruments for righteousness. For sin will have no dominion over you, since you are not under law but under grace. – Romans 6:12-14 ESV It seems quite obvious that Paul knew the power and reality of indwelling sin. He would not have told his readers “let now sin therefore reign in your mortal body” if the possibility for it to happen had not existed. In verse 16 he writes, “Do you not know that if you present yourselves to anyone as obedient slaves, you are slaves of the one whom you obey, either of sin, which leads to death, or of obedience, which leads to righteousness?” (Romans 6:16 ESV). Each and every day, Christ-followers have the choice to give in to and be enslaved yet again by sin or to live in obedience to their God-given, Spirit-empowered new nature. The temptation to give in to sin is an ever-present reality. That's why Paul warned his readers, “Do not let sin control the way you live; do not give in to sinful desire” (Romans 6:12 NLT). There is a conscious choice to be made. We can present our bodies to sin as instruments for unrighteousness or to God as instruments for righteousness. We can allow our sin nature to dictate the behavior of our bodies and determine our actions, or we can, through the power of the Holy Spirit, use our bodies as instruments or tools for God's will. These physical bodies in which we live are the means by which we can accomplish God's work in this world. With these bodies we can love one another or we can lust after one another. We can use these bodies to accomplish God's will or to selfishly fulfill our own. The natural inclination of our sinful nature is to produce some very damaging and destructive fruit. Paul describes the outcome of a life in which sin is allowed to reign. “When you follow the desires of your sinful nature, the results are very clear: sexual immorality, impurity, lustful pleasures, idolatry, sorcery, hostility, quarreling, jealousy, outbursts of anger, selfish ambition, dissension, division, envy, drunkenness, wild parties, and other sins like these” (Galatians 5:19-21 NLT). If you allow sin to reign in your physical body, you will end up obeying its passions and desires. That's why Paul said, “I discipline my body and keep it under control” ( 1 Corinthians 9:27 ESV).
Paul wants us to know that, as believers in Jesus Christ, we have died to sin. It was as if we were crucified alongside Christ. “Those who belong to Christ Jesus have nailed the passions and desires of their sinful nature to his cross and crucified them there” (Galatians 5:24 NLT). Those things are no longer to have control over us. And yet, our physical bodies are constantly tempting us to satisfy its passions and desires. We have to fight constant cravings and desires that are opposed to God's will for us. Paul puts it this way: “The sinful nature wants to do evil, which is just the opposite of what the Spirit wants. And the Spirit gives us desires that are the opposite of what the sinful nature desires. These two forces are constantly fighting each other” (Galatians 5:17 NLT). But Paul also gives us the key to resisting the urges of our flesh: “let the Holy Spirit guide your lives. Then you won’t be doing what your sinful nature craves” (Galatians 5:16 NLT). We can choose to live under the control and influence of the Spirit or we can allow our sin nature, working through our physical bodies, to dictate our behavior. That is why Paul so strongly encourages us to “put to death the sinful, earthly things lurking within you. Have nothing to do with sexual immorality, impurity, lust, and evil desires. Don't be greedy, for a greedy person is an idolater, worshiping the things of this world” (Colossians 3:5 NLT). He warns us, “Run from sexual sin!” (1 Corinthians 6:18 NLT). He encourages us to “throw off your old sinful nature and your former way of life, which is corrupted by lust and deception. Instead, let the Spirit renew your thoughts and attitudes. Put on your new nature, created to be like God—truly righteous and holy” (Ephesians 4:22-24 NLT).
We belong to God. We have been purchased by the blood of His Son. And while these earthly bodies are temporary and will one day be replaced with new, redeemed bodies, we are obligated to use them for God's service as long as we live on this earth. At one time, Paul had used his earthly body to persecute Christians, throwing them into prison and attempting to eliminate them altogether. But once he was redeemed from his old way of life by faith in Jesus Christ, he did everything in his power to make his body his slave and to use it for the glory of God and the good of His Kingdom. Rather than live as a captive to his body's desires, he made his body his slave, using it to accomplish God's will. His sin-prone flesh became an instrument for righteousness. And that is God's call to us. He has not yet redeemed our bodies. But He wants to use them for our good and His glory. Paul describes our current condition in these terms: “We now have this light shining in our hearts, but we ourselves are like fragile clay jars containing this great treasure. This makes it clear that our great power is from God, not from ourselves” (2 Corinthians 4:7 NLT). Sin's dominion or control over us takes place primarily through our physical bodies. It is with our bodies that we fulfill our sinful passions. We use our tongues to lie and deceive. We use our eyes to lust and covet. We use our entire bodies to commit acts of immorality. We use our hands to steal. We use our feet to take us places that are against God's will for us. We use our brains to think inappropriate thoughts and plan unrighteous acts. But because of Christ, we have the capacity to use these fallen bodies as instruments of righteousness. We can use our hands to serve others. We can use our eyes to see needs and meet them. We can use our bodies to accomplish God's will. We can use our tongues to encourage. We can use our feet to take the gospel across the street and around the world.