Introduction
Although sanctification involves spiritual transformation and growth in holiness, the New Testament makes it clear that believers continue to experience an ongoing struggle with sin. The Christian life is therefore marked by both progress in holiness and the persistent tension between the old sinful nature and the new life given by God.
This struggle does not indicate failure or the absence of genuine faith. Rather, it reflects the reality that sanctification is a progressive process, in which believers gradually grow in obedience while still living in a fallen world.
The Tension Between the Flesh and the Spirit
The Apostle Paul describes the Christian life as a conflict between two opposing forces: the flesh and the Spirit. In biblical language, the flesh represents humanity’s fallen nature and its inclination toward sin, while the Spirit represents the transforming power of God within believers.
Paul explains this tension clearly:
“For the flesh desires what is contrary to the Spirit, and the Spirit what is contrary to the flesh.”
— Galatians 5:17
This internal struggle demonstrates that sanctification does not immediately eliminate sinful tendencies. Instead, believers must continually resist the desires of the flesh and rely on the guidance of the Holy Spirit.
The Inner Conflict Described by Paul
One of the most famous passages describing the struggle with sin appears in Paul’s letter to the Romans. In Romans 7, Paul reflects on the tension between his desire to obey God and the continuing presence of sin.
He writes:
“For I do not do the good I want to do, but the evil I do not want to do—this I keep on doing.”
— Romans 7:19
This statement illustrates the profound inner conflict experienced by many believers. While the heart desires to obey God, the influence of sin continues to challenge that desire.
Paul’s reflection reveals that sanctification involves a battle within the human heart, as believers seek to align their lives with God’s will.
Freedom from the Dominion of Sin
Although believers continue to struggle with sin, the New Testament emphasises that sin no longer has ultimate authority over them. Through Christ, believers are freed from the dominion of sin and empowered to pursue righteousness.
Paul expresses this assurance in Romans 6:
“Sin shall no longer be your master, because you are not under the law, but under grace.”
— Romans 6:14
This verse highlights an important distinction. While sin remains present, it no longer defines or governs the believer’s life. Sanctification therefore involves learning to live in the freedom that Christ has already secured.
Repentance and Forgiveness
The Christian struggle with sin also underscores the importance of repentance and forgiveness. Because believers are not yet perfected, they continue to fall short and must regularly turn back to God in repentance.
The New Testament offers reassurance that God’s grace remains available:
“If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness.”
— 1 John 1:9
This promise reveals that sanctification includes a continual cycle of confession, forgiveness, and renewal. Through God’s grace, believers are restored and strengthened to continue their journey toward holiness.
Spiritual Warfare
The struggle with sin is also described in Scripture as a form of spiritual warfare. Believers face not only internal temptation but also external influences that oppose God’s purposes.
The Apostle Paul urges Christians to remain vigilant:
“Put on the full armour of God, so that you can take your stand against the devil’s schemes.”
— Ephesians 6:11
The imagery of spiritual armour illustrates the seriousness of the Christian struggle. Faith, truth, righteousness, and the word of God serve as spiritual resources that enable believers to resist temptation and remain faithful.
Perseverance in the Christian Life
Sanctification requires perseverance. Growth in holiness does not occur instantly but unfolds gradually through faithful obedience, repentance, and dependence on God.
The author of Hebrews encourages believers to remain steadfast in their pursuit of holiness:
“Let us run with perseverance the race marked out for us.”
— Hebrews 12:1
This metaphor portrays the Christian life as a long journey that demands endurance and commitment. Even when believers encounter setbacks, they are called to continue pursuing holiness through the grace of God.
Conclusion
The Christian struggle with sin is an unavoidable aspect of the journey of sanctification. Although believers are transformed through their union with Christ and empowered by the Holy Spirit, they still live in a world affected by sin and must continually resist its influence.
Yet this struggle does not define the Christian life. Through grace, repentance, and the power of the Spirit, believers are able to grow in holiness and persevere in faith. Sanctification is therefore both a battle and a journey, marked by ongoing transformation and the faithful presence of God.
In the next part of this series, we will examine how the doctrine of sanctification developed throughout church history, exploring how different theologians and traditions have understood the process of becoming holy.
References
Grudem, W. (2020) Systematic Theology: An Introduction to Biblical Doctrine. 2nd edn. Grand Rapids: Zondervan.
Moo, D. (2018) The Letter to the Romans. Grand Rapids: Eerdmans.
Peterson, D. (1995) Possessed by God: A New Testament Theology of Sanctification and Holiness. Leicester: Apollos.
Stott, J. (1994) The Message of Romans. Leicester: Inter-Varsity Press.
Wright, N. T. (2013) Paul and the Faithfulness of God. London: SPCK.
The Holy Bible, New International Version (2011). Grand Rapids: Zondervan.