A Primer on Mortification of Sin



Over the years I have written and talked a lot about mortification of sin. In that time I have received occasional questions about the topic. However, in recent months it seems that I have been asked about the subject with a bit more frequency. In fact, I’ve promised a few people that I would write a brief introduction to mortification. Since we are dealing with two older words, let’s call it a primer.

What is mortification?

As I indicated, mortification is not a common word today. And if someone might use it in a sentence they probably are referring to being “mortified” by which they mean that they are embarrassed. When we talk about mortifying sin we are speaking about the original sense of the word. Mortification comes from the Latin mors (death) and facere (to do). In this sense it has to do with putting something to death. Perhaps more literally it is “to make dead.”

What is to be mortified?

In general, sin is to be mortified. In particular, all of the lusts of the flesh that rage against who we as Christians are to be and what we are to do. A couple of Scriptures come to mind (note: the KJV of Romans 8 uses the word “mortify” for “put to death”).

“So then, brothers, we are debtors, not to the flesh, to live according to the flesh. For if you live according to the flesh you will die, but if by the Spirit you put to death the deeds of the body, you will live.” (Romans 8:12–13)

“Put to death therefore what is earthly in you: sexual immorality, impurity, passion, evil desire, and covetousness, which is idolatry. On account of these the wrath of God is coming. In these you too once walked, when you were living in them. But now you must put them all away: anger, wrath, malice, slander, and obscene talk from your mouth.” (Colossians 3:5–8)

How do you do it?

We are reminded in Scripture that the Holy Spirit is the means by which sin is to be put to death. John Owen, in his helpful treatment on the mortification of sin, writes, “A man may easier see without eyes, speak without a tongue, than truly mortify one sin without the Spirit.” Therefore, it follows that the work of mortification is the work of the Holy Spirit in the Christian believer.

A lot of people ask, “But how do I mortify?” I want to quote John Owen here and interact with him a bit as I go because his writing can be a bit dense to some. But, it is so, so good.

To kill a man, or any other living thing, is to take away the principle of all his strength, vigor, and power, so that he cannot act or exert, or put forth any prop actions of his own.

We understand what it means to kill something or someone—it ultimately means to take away its strength and power. We are reminded that indwelling sin is compared to a person, even a living person “the old self” or “old man.”

When we are mortifying sin we are aiming kill all that “inclines, entices, impels to evil, rebels, opposes, fights against God.”

In other words, when we are mortifying sin we are going after all that is evil, desires evil, and lures us toward evil. And we go after it like intolerant, unaccommodating, spiritual assassins.

But we don’t just stop there with a scorched earth sanctification. We must work to cultivate a new desire to replace the fallen lusts:

“by the implanting, habitual residence, and cherishing of a principle of grace that stands in direct opposition to it and is destructive of it. So, by the implanting and growth of humility is paid weakened, passion by patience, uncleanness by purity of mind and conscience, love of this world by heavenly mindedness: which are graces of the Spirit, or the same habitual grace variously acting itself by the Holy Ghost.”

We are working to put off and put on. We are putting sinful vices to death and putting godly virtues to work. The old writers speak of mortification (putting to death) and vivification (putting to life or quickening).

How do we mortify sin? We mortify sin by examining our hearts, minds, and lives in the light of the Word of God and under the conviction of the Holy Spirit. When we see or a fellow believer helps us to see something out of step with the Bible then we work to put it to death.

I should also note that the emphasis of mortification is not simply on the fruit but on the root. It does little good to just simply stop being angry without realizing a strong desire to control people and things. The lust will simply find another way to express itself in its craving for control. Instead we have to deal with the heart issues at the root to see why and how we want to control people and things rather than to trust God and deploy his methods.

Why do you do it?

It is simple: because God’s Word says we must (Rom. 8:13). Let’s not forget this is what believers should want. We want to be holy and reflect Jesus Christ. To want to tolerate sin is an intolerance of holiness. It is an insult of the blood of Christ that bought us (Heb. 10:26ff).

There is also an aspect of the lingering effect of unmortified sin. Owen reminds us that left alone, unmortified sin will do two things: it will weaken the soul and deprive it of its vigor, and it shall darken the soul and deprive it of its comfort and peace. This is what sin does when it reigns in us; it weakens and darkens. Oh, we have great need to mortify sin.

Further, Romans reminds us that if we do not kill sin then we will die. Owen said it well: “Be killing sin or it will be killing you.”

I hope to write more on this subject in the weeks and months ahead. But for now, I do hope that this answered some questions and provides some framework for this important work of the Spirit in the heart of the Christian.

In the meantime, go and pick up Owen’s volume 6 or simply the Puritan paperback. Don’t be intimidated by his outstanding hair; you can read it.