Romans 6:12: Let not sin therefore reign in your mortal body, to make you obey its passions. (ESV)

Surely it is one of the great surprises of the Christian religion that the thing from which we are saved continues to plague us after we have been redeemed. Scripture describes the present reality of Christians on earth as having been redeemed, justified, converted, forgiven, adopted, regenerated, washed, and sanctified. And to these descriptions we could add still more.

Nevertheless, Paul can write to the Romans exhorting them to not let sin reign in their mortal bodies, to make them obey their bodies' passions. And to us, we understand, the same is applicable. There remains in the believer a proclivity, a natural tendency, to allow our bodies to be ruled by sin, so that we obey the passions or desires of sin. As others have said, we are out of Egypt, but Egypt is not out of us. So how do we fight sin?

First Things First

The first thing is honesty. Eph 5:11 says to expose the unfruitful works of darkness. Sin tends to flourish in the dark and wither in the light. So sin should be confessed, not for commiseration, which is simply grieving that it happened without a commitment to kill it. Sin should be confessed in part with a view to tracking its domination over the person. For believers, there should be a trend, however gradual, away from consistently sinning to consistently doing what is right. Our sin is a product both of internal sinful nature and outward corrupting influence (cf. Eph. 2:1ff; Psalm 115:8; Proverbs 1:10-19). Patience is required here both for the discipler and the discipled (2 Tim. 4:1-2; Phil. 2:12-13).

The basic idea is the principle of putting off and putting on, as described in Eph. 4:17-24 and Col. 3:5-17. The specific language of putting off and putting on is found in these verses, but the replacement principle is implicit throughout Scripture. Replacing what is bad with what is good is the basic trajectory of sanctification, and it starts with a focus on Christ. Sin will be our master until Christ is (cf. Rom. 6). As believers, sin will continue to exercise dominion in our hearts where our beliefs, desires, and choices have not yet been subjected to Christ. This is sanctification.

Walking By the Spirit

How does this happen? How do we fish out the areas in our hearts where Christ is functionally not yet our supreme Lord, desire, and aim? In short, I don’t think we worry about fishing those areas as much as we do about one simple thing: walking by the Spirit. Galatians 5:16 is so clear: “But I say, walk by the Spirit, and you will not gratify the desires of the flesh.” What does this mean?

In Gal. 5:25, Paul rephrases it as keeping in step with the Spirit. The way Paul puts it, we are either walking by the Spirit or we are gratifying the desires of the flesh. So when we sin in some outward way, it is not that we are suddenly jumping away from the Spirit and teleporting to a path we weren’t previously on. Instead, an inner fleshly desire that was incubating in the heart has finally given birth to a visible sin (James 1:14-15). This is to say that when we sin, it is not as though we were walking by the Spirit and suddenly drop off. It is to say that in this particular area of our beliefs, desires, and choices, we were never walking by the Spirit, or that fleshly desire would never have been gratified.

I write the previous paragraph because sometimes people are surprised at their sins, and other people are confused by them, but we need to learn to not be. Sin always comes from the heart (Matt. 15:19), and for believers, it comes from a place which, although it is bought and paid for (redeemed), is not yet transformed or conformed to the image of Christ.

This actually should be encouraging. Because when a believer sins, it is a chance for darkness in the heart to be exposed to the light, where it can then be traced back to its roots (wrong beliefs, desires, and choices) and replaced with what is good, true, and beautiful. So we do not need to view sin as a reason to despair but as an opportunity for the marvelous and divine promises of God to be fulfilled by his grace through faith. The cure, at its core, is therefore the practical application of the gospel to this area of his heart.

It is important to take concrete steps to walk by the Spirit rather than by the flesh. But what does this mean? The clue is in Gal. 5:24, where Paul says we who belong to Christ have crucified the flesh with its passions and desires. This connects to the language of discipleship that Jesus used when he talks about taking up our cross and following him. We die to ourselves so that we might live through him.

Putting It into Practice

This connects to the idea of learning to live for God through Christ (cf. Col. 1:29). I conclude, partly from my own practical experience, that to walk by the Spirit must be referring to dependence. Where do we source the influences that shape our hearts (our beliefs, desires, and choices)? We either source them in our selfish desires or from the Spirit. In the case of a person struggling with a particular sin he can’t seem to shake, it must be that in this area of his heart (beliefs/desires/choices), he is depending on and sourcing these things from self rather than from the Spirit, and is therefore gratifying the desires of the flesh.

This is where it gets super practical. We need to look at what are the primary shapers of our hearts (beliefs, desires, and choices) with regard to a particular sin. What wrong beliefs do we have when we commit a particular sin? What wrong desires are in the heart? What wrong choices are being made when this sin is committed?

Once we list some of these things out, the practical question is then to ask, “Where do these things come from?” It could be any number of things (e.g. tv shows, friends, books, social media, etc.). Whatever they are, our dependence on those things needs to be replaced by a practical dependence on the Spirit to source the relevant beliefs, desires, and choices (the ones shaping the heart toward sin) from Christ rather than the wrong sources.

How do we source these things from Christ? The simple answer is what is known as the means of grace. This is why I like David Mathis’ Habits of Grace so much. They are God’s voice (i.e. the Bible, but also faithful teaching/preaching/lyrics/creation), God’s ear (i.e. prayer, private and corporate; silent or voiced; sung, written or spoken), and God’s people (i.e. the church).

The things listed above all declare and/or display the glory of God, and it is via exposure to God’s glory that we are changed (2 Cor. 3:18). These things go into the mind first, but they transform the heart (Rom. 12:1-2).  You might say that the presence of sin reveals a deficiency of exposure to God’s glory, similar to how a vitamin D deficiency means we haven’t spent enough time in the sun. To make a pun, the more the Son shines in our hearts, the fewer places sin will exercise dominion.

I believe that sourcing and submitting our beliefs, desires, and choices in and to Christ is how we walk by the Spirit. Instead of sourcing our power in ourselves, we source it outside of ourselves, from Christ ultimately, who is the image of the invisible God (Col. 1:15). We are so powerless to do this on our own and so dependent on outside help that I think we can picture walking by the Spirit as leaning on him in order to walk as opposed to leaning on nothing or depending on ourselves (cf. Prov. 3:5).

Very practically again, this means that heart change is a gradual thing and not an instantaneous thing. Our hearts are sort of like those bulbs that take a while to reach full brightness. We see as in a mirror dimly, and so we can expect the process of sanctification to be slow but consistent (cf. 1 John 3). The practical application of this is to ask ourselves, “in what ways can I more fully engage in the means of grace in such a way as to specifically target the wrong beliefs, desires, and choices which end up with me committing that sin?"

Putting It All Together

The sum of all these things is an admonishment not to look for a quick fix. The quick fix is beholding the face of God and being glorified, which would mean we have died or Christ has returned. Apart from those two things being the case, we’re left with what I’d call a glorious slog. We’re promised help and success according to our faith, but it requires moment-by-moment devotion of the heart to God. We must learn to live in communion with the Holy Spirit, praying without ceasing, giving thanks in everything, in everything making our requests known to God.

I believe that a right understanding of this ought to lead to some sort of desperation and despair, but it is a desperation for help and a despair of ever making it alone - that is, by our own power. It should lead us to the only one who can offer any hope (cf. Is. 55:1ff) It’s sort of like the old cry when a monarch dies: the king is dead; long live the king! The flesh is dead; we must live as though it really is and start to live under the rule of the new king, King Jesus. But that only happens by depending from the heart on the help and transformation of the Holy Spirit through the means of grace. It is not an instantaneous process, but a gradual one.

We can live in hope that he who sent his Son to die for our sins will continue to forgive us of them and to bring his work to completion in us according to our faith. No amount of personal zeal will make us perfect here, but one day we will be finally glorified and our old nature’s influence on us will be forever eradicated.