It matters little how much strength and skill an army has if, on the day of battle, it underestimates the power of its opponent. Put the wisest generals at its head and the best firepower in its arsenal — still, if such an army misjudges its adversary, it may find itself fleeing in retreat.

So too with us. In the “fight of the faith” (1 Timothy 6:12), every Christian has an almighty force at his disposal, even the Lord of armies himself, who has never lost a battle (Psalm 46:7, 11). Yet if we underestimate the enemy that lives within us — those “passions of the flesh, which wage war against your soul” (1 Peter 2:11) — we may find ourselves face down on the field of war.

“Every morning, we wake up to war.”

The stakes could not be higher. For though our Lord Jesus has gone before us as our great Captain, and though he has disarmed our enemies at his cross and empty tomb, a battlefield still stands between every Christian and God’s kingdom (Romans 8:13). And the banner flying over it reads, “Conquer or be conquered.”

Danger Within

Consider for a moment the enemy we call “indwelling sin.” Remember, first, the position of this enemy. The danger we are up against is not a danger ahead or a danger behind, but a danger within. However holy we may be, we carry with us, wherever we go, “sin that dwells within” (Romans 7:20), a force that fights “against the Spirit” (Galatians 5:17). At work and at home, in public and in private, at midnight and at noon, this enemy is always with us.

Remember also the strength of this enemy. It was indwelling sin that lured Demas back to the world after years of service to Christ (2 Timothy 4:10). It was indwelling sin that disgraced so many kings of Israel after such wonderful beginnings (see, for example, 2 Chronicles 26:16). It was indwelling sin that gravely wounded even the mightiest of men: Noah and Moses, David and Hezekiah, Peter and Barnabas. No matter how long we have walked with Christ, and no matter how firm our faith, every Christian is within the firing range of indwelling sin.

Consider, finally, the stamina of this enemy. The apostle Paul waited until the end of his life to say, “I have fought the good fight, I have finished the race, I have kept the faith” (2 Timothy 4:7). Among the slain are many who, contrary to Paul’s example, rested in victory before its time — whose early successes misled them to give up watching, give up praying, give up confessing, until they found themselves giving up altogether.

Weapons for the War

Remembering the power of our indwelling sin is not pleasant. Far more comfortable to talk of Christian victory and pretend that all is well. Yes, far more comfortable — and far more deadly. For if we refuse to look our foe in the face, we will likely refuse to face it with the weapons God provides.

If, on the other hand, we regularly consider the power of our indwelling sin, we will walk onto the battlefield clad with the armor of God. We will learn to expect a daily battle, to walk humbly, to kill sin at the start, and to keep near our Captain.

Expect a daily battle.

Our enemy’s position within us reminds us that our battle is a daily one. Unlike some armies, we cannot retreat for a season to escape the clamor of conflict. Every morning, we wake up to war.

This reminder, so disheartening at first, ought to cheer every embattled saint. For if we feel the clash of armies inside of us, and find our best resolves opposed at every step, and yet still press on ahead — well then, as J.C. Ryle writes, “We are evidently no friends of Satan. Like the kings of this world, he wars not against his own subjects” (Holiness, 72).

“God’s Spirit makes himself known in us not by the absence of enemies, but by the presence of our warfare against them.”

Expect, then, to rise up from a moving hour in Scripture and prayer, only to find your mind assaulted and your affections thrown off course. Expect the ground you gained yesterday to be challenged again today. Expect to be startled and confounded by dark impulses rising from within. And know that such opposition does not signal your defeat, but rather marks the beginning of the battle.

God’s Spirit makes himself known in us not by the absence of enemies, but by the presence of our warfare against them (Galatians 5:17–18).

Walk humbly.

As we consider the men and women stronger than we whom sin has successfully defeated, humility is the only sane response. Better to face our foe trembling and dismayed than to face him proud. Better to think ourselves capable of every sin, and to perpetually stand our guard, than to fancy ourselves strong in our own strength. For in the battle against sin, as in everything else, pride comes before a fall (Proverbs 16:18).

Those who walk humbly are not ashamed to pray every morning, “Lead [me] not into temptation” (Matthew 6:13). Their ears are awake to the warnings, strewn everywhere in Scripture, to “take heed lest [you] fall” (1 Corinthians 10:12), “be on your guard” (Luke 12:15), and “be watchful” (1 Peter 5:8). They are not too proud to stay near their brothers in arms, confessing their failures and asking for help.

The safest soldiers on the battlefield are the humblest ones: those who feel deep down that without Christ they can win no war (John 15:5) — yet with him, every war (Philippians 4:13).

Kill sin at the start.

Perhaps nothing shows more clearly what we think of sin’s strength than how we handle its first approaches. An army may take its time in rising up against a small army — but if the enemy is mighty, the watchmen sound the alarm long before the first shot is fired.

John Owen writes,

The great wisdom and security of the soul in dealing with indwelling sin is to put a violent stop unto its beginnings, its first motions and actings. Venture all on the first attempt. Die rather than yield one step unto it. (Indwelling Sin, 208)

Venture all upon the first attempt: dispel the first wisp of a fantasy, crush the first impulse toward greed, attack the first inclination toward gossip, oppose the first craving for another drink, douse the first flame of anger. In other words, “make no provision for the flesh” (Romans 13:14).

Killing sin in these first moments may seem like a small victory, but the narrow way to heaven is filled with small victories — and the broad road to hell is paved with small compromises. So don’t despise the small battles you face again today.

Keep near your Captain.

All our expectations, humility, and efforts will prove vain, however, unless we keep near our Captain. Apart from Christ, all our weapons against sin are just so many plastic swords. But in Christ, we handle real swords in our warfare.

“All our safety, all our wisdom, all our peace and comfort rests in this: keep near Christ.”

We would do well to despair if we faced our enemies on our own. But what need have we for fear if our Lord Jesus is with us? Why shrink away if we stand behind the shield of our greater David? The King who will one day slay the lawless one with the breath of his mouth is more than able to subdue our enemies within (2 Thessalonians 2:8).

All our safety, all our wisdom, all our peace and comfort rests in this: keep near Christ. Keep near his cross, where he canceled all our guilt. Keep near his empty tomb, where he broke sin’s power and reign. Keep near his nail-scarred hands, where he pleads his brothers’ cause. Keep near his throne of grace, where he holds well-timed help for every crisis (Hebrews 4:16).

All Who Fight Conquer

Conquer or be conquered: this is the prospect before us all this side of glory. But we dare not imagine that the conquering rests on us, much less that Christ watches, unconcerned, to see the outcome of the battle. Richard Sibbes writes,

The victory lies neither in our own strength to get it, nor in our enemies’ strength to defeat it. If it lay with us, we might justly fear. But Christ will maintain his own government in us and take our part against our corruptions. They are his enemies as well as ours. . . . We have more for us than against us. What coward would not fight when he is sure of victory? None is here overcome but he that will not fight. (The Bruised Reed, 122)

Wherever you are in the fight against sin — whether in the thrill of victory or the throes of defeat — remember: as many as your foes are, you have far more for you than against you if you are Christ’s (2 Kings 6:16; 1 John 4:4), and you cannot be conquered if you only keep fighting. So come again to your Captain, take fresh courage, and go forth to battle.