The apostle Paul recognized the fact there is an internal battle within each one of us; every believer has an “enemy within” that we must fight. This lifelong battle between the flesh and the Spirit will rage until our death. Romans 7:21–23 addresses the enemy within: “So I find this law at work: Although I want to do good, evil is right there with me. For in my inner being I delight in God’s law; but I see another law at work in me, waging war against the law of my mind and making me a prisoner of the law of sin at work within me.” Paul understood that his fleshly nature would never conform to God’s will. No matter how much he might want to obey God in every way, he was fighting the “evil . . . right there with me,” the enemy within.
Jesus also spoke of the enemy within, in different terms. Addressing His sleepy disciples in Gethsemane, Jesus admonished them to pray and gave a reason they must pray: “The spirit is willing, but the flesh is weak” (Mark 14:38). There’s no way to ignore it—we are bound to a fleshly, selfish nature as long as we are in this earthly existence. It is the enemy within that would keep us from doing what we should.
Athletes in training know firsthand the struggle against the enemy within, and many athletes speak of their own worst enemy being themselves. To be a successful athlete, one must overcome mental obstacles, self-doubt, and the simple desire to take the easy way. Paul must have been a sports enthusiast, for he uses comparisons to sports and how athletes discipline their bodies to bring them under control so as to win the prize (see 1 Corinthians 9:24–27 and 2 Timothy 2:5). We as children of the light must do the same, denying the unhealthy cravings of the flesh in order to gain a spiritual advantage. Our training is much more important than that of Olympic athletes, even, for the stakes are much higher in the spiritual realm. “Everyone who competes in the games goes into strict training. They do it to get a crown that will not last, but we do it to get a crown that will last forever” (1 Corinthians 9:25). As we practice self-control, the fleshly appetites grow weaker, and, as we feed the spirit, the things of the Spirit within us will rule.
Jesus said, “You are defiled by what comes from your heart,” that is, what comes from within (Mark 7:15, NLT). And we know that “the acts of the flesh are obvious: sexual immorality, impurity and debauchery; idolatry and witchcraft; hatred, discord, jealousy, fits of rage, selfish ambition, dissensions, factions and envy; drunkenness, orgies, and the like. I warn you, as I did before, that those who live like this will not inherit the kingdom of God” (Galatians 5:19–21). Our flesh will rear its ugly head in many different ways; some ways are more deceitful than others, and it’s good to know ourselves so we can watch for this “enemy within.”
The book The Two Towers by J. R. R. Tolkien has a passage in which the conflicted and wretched Gollum has a dialogue with himself (Book IV, chapter 2). He bounces from fearful to sinister, alternating from vulnerable to spiteful, as he struggles to fight the enemy within himself. That passage can serve as an illustration of the believer’s daily skirmish with the flesh. “The flesh desires what is contrary to the Spirit, and the Spirit what is contrary to the flesh. They are in conflict with each other, so that you are not to do whatever you want” (Galatians 5:17).
How can we overcome the enemy within? Scripture says we must deny ourselves; in fact, all those who desire to follow Christ must take up their cross (Luke 9:23; 14:27). We must learn to say “no” to the desires of our fallen nature. “[The grace of God] teaches us to say ‘No’ to ungodliness and worldly passions, and to live self-controlled, upright and godly lives in this present age” (Titus 2:12).
To successfully fight the enemy within, we must understand the true power of Christ’s death: “‘He himself bore our sins’ in his body on the cross, so that we might die to sins and live for righteousness” (1 Peter 2:24). Based on the death of Christ, we consider ourselves dead to sin and alive to God: “Our old self was crucified with him” (Romans 6:6; cf. verse 11).
And, to conquer the enemy within, we must yield to the Holy Spirit: “Walk by the Spirit, and you will not gratify the desires of the flesh” (Galatians 5:16). The power to win does not come from within us, as we are just jars of clay; rather, “this all-surpassing power is from God” (2 Corinthians 4:7). As Paul fought the enemy within himself, he kept his eyes on his Savior: “What a wretched man I am! Who will rescue me from this body that is subject to death? Thanks be to God, who delivers me through Jesus Christ our Lord!” (Romans 7:24–25).