Why do Christians still sin after salvation?

Every true Christian would love to be free from the temptations and struggles that a life of sin has brought upon us; we would all love to be just like Jesus Christ. When we surrender our lives to Christ, we are immediately justified in the eyes of God. We are fully forgiven of all our sin and declared righteous (Ephesians 1:3–14). However, even though God could make us perfect in an instant, He chooses instead to work in us and through us to conform us to Christ's image (Romans 8:29). This means that we still sin after salvation. God is faithful to bring His work in us to completion (Philippians 1:6), but becoming righteous (sanctification) is a lifelong process. We see this reality throughout the New Testament.

For example, Paul described the Israelites as having minds that were hardened and a veil covering their hearts when they heard the Word of God (2 Corinthians 3:14–15). "But" writes Paul, "When one turns to the Lord, the veil is removed" (2 Corinthians 3:16). This means that we see more clearly; our hearts and minds are no longer hardened toward God. However, this does not mean we are perfect. Paul goes on to say that we are all, as a result of God's grace, being transformed from one degree to another into the image of Christ (2 Corinthians 3:18). As a result, we must "Put off your old self, which belongs to your former manner of life and is corrupt through deceitful desires, and be renewed in the spirit of your minds, and put on the new self, created after the likeness of God in true righteousness and holiness" (Ephesians 4:22–24).

We recognize that we still sin even after we are saved. But what are we to do about it? This requires faith, patience, and endurance—all of which are supplied by our gracious Lord and Savior, Jesus Christ (Philippians 2:12–13; 2 Peter 1:3–11).

Practically, we can start by setting our minds on the things of God (Matthew 16:23; Colossians 3:1–4). Scripture says, "Do not be conformed to this world, but be transformed by the renewal of your mind, that by testing you may discern what is the will of God, what is good and acceptable and perfect" (Romans 12:2). The more we are immersed in the Word of God, the more we will know and love God. The more our thinking is centered on the truth of God, the more our attitudes and actions will line up with His character. James 1:22 counsels, "Be doers of the word, and not hearers only, deceiving yourselves." We don't just read and study God's Word for intellectual knowledge; we actually allow it to do its work in our hearts and apply it to our lives. We need to genuinely seek to "put off your old self" and "put on the new self" (Ephesians 4:22–24; cf. Ephesians 4:17—5:21; Colossians 3:1–17; Galatians 5:16–26), knowing all the while that the work of transformation belongs to the Holy Spirit.

We can also recognize that we are in a battle. Peter warns us to be alert: "Be sober-minded; be watchful. Your adversary the devil prowls around like a roaring lion, seeking someone to devour" (1 Peter 5:8). Ephesians 6:11 says, "Put on the whole armor of God, that you may be able to stand against the schemes of the devil." It often feels like the more we strive to do what is right in the eyes of God, the more Satan will attack and try to prevent us from righteous living. There is a war being waged between the new desire of your heart and the old desire of your flesh, and Satan prowls in that divide. When we stand firmly in our faith, focus on God, immerse ourselves in His Word, and seek Him out in constant prayer, we will not be so easily tempted by the desires of our flesh or so prone to Satan's snare.

Christian community is also vitally important. Hebrews 10:23–25 says, "Let us hold fast the confession of our hope without wavering, for he who promised is faithful. And let us consider how to stir up one another to love and good works, not neglecting to meet together, as is the habit of some, but encouraging one another, and all the more as you see the Day drawing near." Galatians 6:1–2 encourages, "Brothers, if anyone is caught in any transgression, you who are spiritual should restore him in a spirit of gentleness. Keep watch on yourself, lest you too be tempted. Bear one another's burdens, and so fulfill the law of Christ." James 5 talks about confessing our sins to one another and praying for one another (James 5:15–20). We do not stand strong in the Lord alone. Believers encourage one another in faith and in truth. The process of sanctification happens in community and often through community.

The life of a Christian is a fight (2 Timothy 4:7), a constant battle between the desires of our old selves trying to reclaim control and the desires of our spirits to be like Christ. Believers have fought this battle for millennia, and the accounts of God's faithfulness in their lives encourage us. In the book of Hebrews, the preacher writes, "Therefore, since we are surrounded by so great a cloud of witnesses, let us also lay aside every weight, and sin which clings so closely, and let us run with endurance the race that is set before us, looking to Jesus, the founder and perfecter of our faith, who for the joy that was set before him endured the cross, despising the shame, and is seated at the right hand of the throne of God" (Hebrews 12:1–2). We must cast off the things that tempt us, put aside the things that distract us, and focus our attention on the race that is set before us; we must focus on Christ.

We still sin after salvation, but we fight against it. We do not seek to tame our sin, but to put it to death (Matthew 5:29–30; Colossians 3:5–8). We steep our minds in truth, knowing that "every good and every perfect gift is from above, coming down from the Father of lights" (James 1:16–18) and that sin only leads to death (James 1:12–15). We recognize that Jesus is the way of true life (John 10:10) and we seek to walk as He calls us to (John 15:1–17).

Jesus has accomplished the work of salvation and God is faithful to complete it in us (Romans 8:29–30; 1 Peter 1:3–12). "There is therefore now no condemnation for those who are in Christ Jesus. For the law of the Spirit of life has set you free in Christ Jesus from the law of sin and death" (Romans 8:1–2). In Romans we read, "If Christ is in you, although the body is dead because of sin, the Spirit is life because of righteousness" (Romans 8:10). We are not fighting this battle alone because we have the Spirit of Christ in us! As you continue to grow and mature in Christ, your desire to be more like Him will increase, and in turn, the desires of your flesh will decrease. However, we will never attain perfection in this life, but when we leave this corrupt world, we will be perfected and our earthly body will be replaced with a glorious and perfect body (Philippians 3:21). While sin is a reality of our lives presently, one day we will be with God and sin will be no more.