Modern Terminology for Mortifying Sin
The concept of "mortifying sin" refers to the active process of putting to death sinful desires and actions within a believer's life. This theological term is rooted in biblical exhortations, particularly in the Pauline epistles. For instance, Colossians 3:5 directly commands, "Mortify therefore your members which are upon the earth" [5]. The Greek term translated as "mortify" means to "make a corpse of" or "make dead" [6]. This is not a call to harm the physical body, but rather to subdue the "body of sin" or "indwelling sin," which consists of sinful actions and desires that operate through the physical members [5].
The call to mortify sin is often presented as a logical consequence of a believer's spiritual union with Christ. As Matthew Henry notes on 1 Peter 4:1, the apostle draws an inference from Christ's suffering in the flesh to the believer's need for "mortification of sin." Just as Christ suffered in his human nature, believers are exhorted to "arm and fortify yourselves likewise with the same mind, courage, and resolution" against sin [1]. This implies a deliberate and resolute effort to combat sinful inclinations.
In scholastic theology, particularly as articulated by Thomas Aquinas, sin is understood in terms of its nature and consequences. Mortal sin, for example, involves both an "aversion from God and adherence to a created good" [3]. The stain of sin results from the privation of grace, and the debt of everlasting punishment is incurred [3]. While Aquinas discusses the return of forgiven sins through subsequent sin, the broader framework of sin and its removal underpins the necessity of mortification. He also distinguishes between mortal and venial sins, with mortal sin metaphorically referring to the "death of the soul" [4]. The act of mortification, therefore, aims to counteract these sinful tendencies that lead away from God.
The Reformed tradition emphasizes that mortification is a continuous process for those who have been spiritually regenerated. John Gill explains that the "members" to be mortified are not the natural body but "the sins of the flesh, or sinful actions" [5]. These are the actions generally performed by the natural body's members, through which the "law of sin" operates [5]. Jamieson, Fausset, and Brown further clarify that believers are to "habitually repress and do violence to corrupt desires" that use the body's members as instruments [6]. This daily "deadening" of sinful members follows from the spiritual death with Christ experienced at regeneration [6].
The ultimate design of Christ's work is not merely the pardon of sin but also reconciliation with God, which "involves or secures conformity to his image and intimate fellowship with Him" [2]. Therefore, mortification is an essential aspect of this ongoing transformation into Christ's likeness. It is a practical outworking of the believer's new life in Christ, where the old self and its sinful practices are actively put to death.
Early Christian writers also addressed the practical aspects of repentance, which aligns with the concept of mortification. Tertullian, for instance, discusses exomologesis, a public confession of sins to the Lord, not because God is ignorant of them, but as an external act accompanying inward repentance [7]. This outward manifestation of repentance demonstrates a commitment to turning away from sin, which is a core component of mortification. The process of mortifying sin is thus understood as a lifelong spiritual discipline, integral to Christian discipleship and the pursuit of holiness.
Sources
- 1 Peter (Nonconformist/Puritan) “Matthew Henry on 1 Peter 4:1: The apostle here draws a new inference from the consideration of Christ's sufferings. As he had before made use of it to persuade to patience in suffering, so here to mortification of sin. Observe, I. How the exhortation is expressed. The antecedent or supposition is that Christ had suffered for us in the flesh, or in his human nature. The consequent or inference is, "Arm and fortify yourselves likewise with the same mind, courage, and resolution." The word flesh in the former part of the verse signifies Christ's human nature, but in the latter part it signifies m”
- CCEL (Reformed (Old Princeton)) “Charles Hodge, Systematic Theology, Vol. 2, section 103: looking for of judgment.” It was pardon, therefore, founded upon the expiation of sin, that was secured by the sacrifice of Christ. And this is declared to be the only possible means by which our guilt can be removed, or the justice of God satisfied. It is to be always borne in mind, however, that the end of expiation is reconciliation with God, and that reconciliation with God involves or secures conformity to his image and intimate fellowship with Him. The ultimate design of the work of Christ is, therefore, declared to be to “bring us”
- theology (Catholic (Scholastic)) “Aquinas, Summa Theologica, Third Part (Tertia Pars), Of the Return of Sins Which Have Been Taken Away by Penance, Art. 1: Article: Whether sins once forgiven return through a subsequent sin? I answer that, As stated above (Question [86], Article [4]), mortal sin contains two things, aversion from God and adherence to a created good. Now, in mortal sin, whatever attaches to the aversion, is, considered in itself, common to all mortal sins, since man turns away from God by every mortal sin, so that, in consequence, the stain resulting from the privation of grace, and the debt of everlasting puni”
- theology (Catholic (Scholastic)) “Aquinas, Summa Theologica, First Part of the Second Part (Prima Secundae), Of Venial and Mortal Sin, Art. 1: Article: Whether venial sin is fittingly condivided with mortal sin? I answer that, Certain terms do not appear to be mutually opposed, if taken in their proper sense, whereas they are opposed if taken metaphorically: thus "to smile" is not opposed to "being dry"; but if we speak of the smiling meadows when they are decked with flowers and fresh with green hues this is opposed to drought. In like manner if mortal be taken literally as referring to the death of the body, it does not impl”
- Colossians (Baptist/Reformed) “John Gill on Colossians 3:5: Mortify therefore your members,.... Not your bodies, as the Ethiopic version reads, nor the members of the natural body, but of the body of sin, indwelling sin; which as a body consists of various members, which are parts of it, rise out of it, and are used by it, as the members are by the body; and intend the sins of the flesh, or sinful actions, which are generally performed by the members of the natural body, in which the law of sin is, and by which it operates; so that the mortification the saints are here exhorted to, in consideration of having a spiritual lif”
- Colossians (Presbyterian) “Jamieson, Fausset & Brown on Colossians 3:5: Mortify--Greek, "make a corpse of"; "make dead"; "put to death." therefore--(See on Col 3:3). Follow out to its necessary consequence the fact of your having once for all died with Christ spiritually at your regeneration, by daily "deadening your members," of which united "the body of the sins of the flesh" consists (compare Col 2:11). "The members" to be mortified are the fleshly instruments of lust, in so far as the members of the body are abused to such purposes. Habitually repress and do violence to corrupt desires of which the members are the”
- Schaff ANF/NPNF (Patristic) “ANF Vol 3: Tertullian — CHAP. IX.--CONCERNING THE OUTWARD MANIFESTATIONS BY WHICH THIS SECOND REPENTANCE IS TO BE ACCOMPANIED.: The narrower, then, the sphere of action of this second and only (remaining) repentance, the more laborious is its probation; in order that it may not be exhibited in the conscience alone, but may likewise be carried out in some (external) act. This act, which is more usually expressed and commonly spoken of under a Greek name, is <greek>exomologhsis</greek>,[1] whereby we confess our sins to the Lord, not indeed as if He were ignorant of them, but inasmuch as by conf”