"So then those who are in the flesh cannot please God" (Rom. 8:8).
When we speak of the Christian life as a battle, who are we fighting? While we certainly oppose the world and the minions of Satan, our chief war is waged against ourselves, against the remaining corruption in our souls. Even though Christ has redeemed us, the old has gone and the new has come, our sanctification remains incomplete. We still retain trappings of the old man—the sinful nature that once held us in bondage, but now remains as a persistent irritant in our effort to please God.
Paul described the opponents in this battle as the spirit and the flesh. While the sinful nature remains throughout our lives until we are freed from our mortal bodies, Paul is not attributing the evil within us to the physical realm. The body we have is not evil. The evil in us, the flesh that brings forth all kinds of iniquity, is our sinful nature. Because the flesh can lead a Christian astray, we must take this battle between the flesh and the spirit very seriously. We cannot blame our sinful behavior solely on evil from without—the world and Satan. Martin Luther once said that he feared what was within him more than what was without. If we all took that point of view, we would live more soberly.
If you have been redeemed by Christ, you have the power of the Holy Spirit to overcome your sinful nature. Paul teaches us in Romans 8 to live according to the Spirit. To do so one must think on what the Spirit desires and not on what the sinful nature desires. God has given us His Word that we might know what He desires of us—to live in righteousness and truth, in His ways, and according to His statutes. Paul says that the acts of the sinful nature are obvious: “sexual immorality, impurity and debauchery; idolatry and witchcraft; hatred, discord, jealously, fits of rage, selfish ambition, dissensions, factions and envy; drunkenness, orgies and the like” (Gal. 5:19–21). Those who live like this will not inherit the kingdom of heaven. Every Christian must put these deeds to death and bring to life the fruit of the Spirit: “love, joy, peace, patience, kindness, goodness, faithfulness, gentleness and self-control.” In your Christian walk, do not be controlled by the sinful nature, but walk in purity and truth according to the Spirit.
In what areas of your life have you achieved the most victory over the flesh? What areas have you not achieved victory? In those areas where you struggle the most between the flesh and spirit, carefully consider what you may do to overcome the sinful nature. Make a specific measurable plan to keep yourself accountable.