What is sin?

As one of the most commonly misunderstood doctrines, sanctification, in its truest form, is the process of learning and re-learning the gospel continually in your heart and mind. Sanctification is the art of becoming like Christ is remembering, and repeating that remembrance for a lifetime. With that in mind, I’d like to hasten to another question that is often asked and even more so misunderstood. That is, “What is sin?” We’re not asking, “What does sin look like?” Rather, “What is sin, in its essence?” It’s important to define “sin” and what it is, so that we can more fully and clearly understand what our role in sanctification is. The root of our problem isn’t our behavior, but our belief (or lack thereof). At the core of all of mankind’s problems and struggles and hardships and brokenness lies the problem of the unbelieving heart. “The sin to be ultimately expelled,” writes theologian Gerhard Forde, “is our lack of trust, our unbelief.”1

Every sin begins as a temptation to disbelieve in what is already yours in the gospel, going all the way back to the Genesis and the sin of Adam and Eve in the garden. Satan’s goal, just as it was then, so it is now, remains to cause you to doubt and distrust what Jesus has already secured for you on the cross. When Christ cried “It is finished” while hanging and dying on that tree, he assured our salvation and cemented our hope in his ransom and his deliverance for us. Our pardon from sin was sealed and secured on the cross! Everything we need and desire is anchored in the gospel, in Jesus’s finished work of redemption for his creation.

We sin and we fail, then, because we distrust and disbelieve the gospel, and instead trust more in the promises of sin. I should say false-promises of sin, for that’s what they are: expectations that are never met and affirmations that are never fulfilled. Regardless of the temptation, regardless what you think you might get out it, sin will never, ever deliver! It will always leave you wanting more. Sin always over-promises and under-delivers.

Indeed, as Charles Spurgeon says, “Sin is a madness, disqualifying the mind for sober judgment; a blindness, rendering the soul incapable of appreciating moral beauty; it is in fact such a perversion of all the faculties, that under its terrible influence men will ‘call evil good, and good evil; they will put darkness for light, and light for darkness; bitter for sweet, and sweet for bitter.’”2 And so it is in the world in which we live. People are constantly chasing after “more”: more pleasure, more power, more prestige, more fame, more wealth, more, more, more! Because of sin and his rejection of God, mankind is running on the endless hamster-wheel of “getting.” Always he is seeking for himself. The true nature of sin is always and eternally self-focused. Sin will always point you to yourself — “What can I get?” “What do I need?” “How’s this going to affect me?” “What’s in it for me?” “What’ve you done for me lately?” etc., etc.

The sad part is that Christians have, likewise, determined the answer is themselves. We’ve conjured up the idea that, “Living like Jesus is up to me, it’s on my shoulders!” We’ve given into the notion that the gospel itself isn’t enough to satisfy, that grace is too easy and too good to be true. That we must find or fabricate our own satisfaction and our own salvation. Christians are often “seasoned ‘do-it-yourselfers.’” We’re experiences self-salvation and self-justification architects who determine it easier to make copious lists of “to-dos” and “not-to-dos” than to just trust in what Jesus has done. This idea that I can turn to myself to fix myself also avoids the truest reality of sin: that what’s unclean, unholy, and unseemly is already inside of you!

If you look at the very important passage in Mark 7:14–23, you will find that this is precisely the point that Christ was making. “It is what comes from inside that defiles you. For from within, out of a person’s heart, come evil thoughts, sexual immorality, theft, murder, adultery, greed, wickedness, deceit, lustful desires, envy, slander, pride, and foolishness. All these vile things come from within; they are what defile you.” (Mk 7:20–23) This reveals the startling truth that external things — peers, circumstances, etc. — can’t make us sin; they merely reveal the sin that’s already inside us.

It must be understood, as Matt Chandler rightly notes, that “you don’t do sinful acts to make yourself a sinner; you’re a sinner, so you do sinful acts.” This is huge! This is why just giving you a list of things to avoid, why fashioning a Christian “to-do” or “not-to-do” list wouldn’t address or affect the heart or the root of the problem. The heart of the human problem is the problem of the human heart. But, further still, as Tim Keller says, “Sin isn’t only doing bad things, it is more fundamentally making good things into ultimate things. Sin is building your life and meaning on anything, even a very good thing, more than on God.”

We’re dragged into sin by an internal push or impulse, not an external pull. Therefore, the “fruits” of sin (Mk 7:21–22; Gal 5:19–21; Col 3:5–9) are battled not just by working to avoid them, that is, being sanctified from them, but by believing more and more that all we have and everything we need is ours in Christ. The more we’re satisfied with everything that’s already ours in Christ Jesus and the more we’re reveling and relishing and resting and rejoicing in God’s gospel of fathomless grace, the weaker the influence of Satan will be, and the less likely it will be that we give in to the false-promises of sin. If we’re truly caught up and captured by the amazing grace of Jesus, anything else this world promises you or offers you will be nothing but rubbish, totally worthless.

So, what does this mean for us who are battling sin? It means that believing in the reality of the gospel, that we’re absolutely nothing and that Jesus is everything, enables us to lean on the power of God to combat the temptations and doubts that Satan attacks us with. Since our problem lies primarily internally, not externally, to turn to yourself for the answer is to resort to a broken, imperfect solution. There’s nothing good within us (Mk 7:14–23; Ps 14:3; Is 53:6; Ecc 7:20), so to trust in yourself is foolish. Our only option to fight sin is to continually, daily, hourly turn to Jesus — the one, true Answer, Solution, and Remedy for lost and dying souls.

All our toiling and working and striving to avoid sin and become like Jesus is futile and vain without God being the Initiator and Keeper and Finisher of it. (Ps 127:1–2; Heb 12:1–2) Successful Christian living is greater and greater dependence on Jesus’s performance for us, and greater and greater forgetfulness of ourselves. Avoiding sin and living the sanctified life is all about reproducing and re-learning the gospel in your heart and mind and soul everyday (Jn 3:30) — it’s a constant remembrance of what Jesus did. Therefore, when temptations come, shout aloud with that great Reformer, Martin Luther:

When the devil throws your sins in your face and declares that you deserve death and hell, tell him this: “I admit that I deserve death and hell, what of it? For I know One who suffered and made satisfaction on my behalf. His name is Jesus Christ, Son of God, and where he is there I shall be also!”


Gerhard Forde, The Preached God: Proclamation in Word and Sacrament, edited by Mark C. Mattes and Steven D. Paulson (Grand Rapids, MI: Eerdmans, 2007), 236.


Charles Spurgeon, The Saint and His Saviour: The Progress of the Soul in the Knowledge of Jesus (Houston: Christian Focus, 1989), 22