Soon after becoming a Christian, I started wondering if I really was a Christian. The first doubt struck unexpectedly, like lightning from a cloudless sky. Am I real? I seemed to love Jesus. I seemed to trust him. I seemed to bear the marks of a changed life. But, the thought crept in, so too did Judas.

Though the long night of wrestling slowly passed, I emerged from it like Jacob, limping into the daylight. Assurance has been, perhaps, the main question, the chief struggle of my Christian life over the years, sending me searching for what Paul and the author of Hebrews call “full assurance” (Colossians 2:2; Hebrews 10:22).

The topic of assurance is complex, to put it mildly. Genuine Christians doubt their salvation for many different reasons, and God nourishes assurance through several different means. So the needed word for one doubter often differs from the needed word for another. Nevertheless, for those who find themselves floundering, as I did, perhaps unsure what’s even happening to them, a basic guide to assurance may prove useful.

Possibility of Assurance

By assurance, I simply mean, to borrow a definition from D.A. Carson, “a Christian believer’s confidence that he or she is in right standing with God, and that this will issue in ultimate salvation.” Assured Christians can say, with Spirit-wrought conviction, not only “Christ died for sinners” but “Christ died for me.” Though sin may assault them, and Satan may accuse them, they know themselves forgiven, beloved, and bound for heaven. And the first word to offer about such assurance is simply this: it’s possible.

Your faith may feel small, and your hold on Christ shaky. Even still, it is possible for you to feel down deep that he will never cast you out (John 6:37). It is possible for you to cry “Abba!” with the implicit trust of God’s children (Romans 8:15–16). It is possible for you to “rejoice with joy that is inexpressible and filled with glory” (1 Peter 1:8). It is possible for you to have “confidence for the day of judgment” (1 John 4:17) — indeed, to “know that you have eternal life” (1 John 5:13).

God’s desire for his people’s assurance, even for the most fragile of them, burns brightly through the Scriptures. He has knit assurance into his very name, whether old covenant (Exodus 34:6–7) or new (Matthew 1:21). He has spoken assurance in promise upon promise from a mouth that “never lies” (Titus 1:2). And as he once wrote assurance with a rainbow (Genesis 9:13–17), and flashed assurance through the stars (Genesis 15:5–6), so now he has sealed assurance with the greatest sign of all: the body and blood of his dear Son. Week by week, we eat the bread and drink the cup of his steadfast love in Christ (Matthew 26:26–29).

If God’s new covenant is sure (and it is), if his promises are true (and they are), and if his character cannot change (and it can’t), then full assurance is possible for everyone in Christ, no matter how strong our present fears.

Enemies of Assurance

If, then, Scripture testifies so powerfully to the possibility of assurance, why does anyone ever lack assurance — and why do some seem to struggle with it ongoingly? Because Christian assurance is not only possible, but opposed. Of the enemies that assail us, three are chief: Satan, sin, and our broken psychology.

Satan

We might expect “the accuser of our brothers, . . . who accuses them day and night before our God” to war against the Christian’s peace (Revelation 12:10). And so he does.

In his classic on assurance, Religious Affections, Jonathan Edwards reminds readers that the devil assaulted even the assurance of Jesus (172). “If you are the Son of God, command these stones. . . . If you are the Son of God, throw yourself down” (Matthew 4:3, 6). The Father had just said, “This is my beloved Son” (Matthew 3:17), but the devil loves to trade his own if for God’s is.

“The devil knows that well-assured Christians threaten the domain of darkness more than any other.”

Many a true Christian has, in turn, heard that dreadful if: “If you are a Christian, why do you sin so much? Why is your faith so small? Why is your heart so cold?” And though Satan’s charges cannot condemn those whom God has justified (Romans 8:33), they certainly can ruin our comfort.

The devil knows that well-assured Christians threaten the domain of darkness more than any other. And so, he protects his property with one of his most-used weapons: doubt.

Sin

Alongside Satan, Scripture presents sin as one of the foremost enemies of assurance. Now, of course, assurance in this life always coexists with sin. “If we say we have no sin, we deceive ourselves, and the truth is not in us” (1 John 1:8). Nevertheless, habitual sin, unrepentant sin, or particularly grievous sin darkens our assurance as surely as drawn curtains darken a room — and it should.

“By this we know that we have come to know him,” the apostle John writes, “if we keep his commandments” (1 John 2:5). And therefore, when a pattern of commandment-keeping gives way to commandment-breaking, and a pattern of repentance to stubbornness, and a pattern of confession to secrecy, we cannot “know that we have come to know him” with the same confidence as before. We may be secure in Jesus’s grasp, as Peter was even when he denied his Lord, but our sense of that security is rightly weak until we “have turned again” (Luke 22:31–32), and again have heard his pardoning voice (John 21:15–19).

Psychology

Finally, our own psychology plays an influential, but often overlooked, role in assurance. (By psychology, I refer generally to matters of temperament, patterns of thought, and self-reflection.) Assurance is not only a spiritual phenomenon, but a psychological one: its strength depends on a rightly calibrated conscience, mature self-awareness, and the ability to distinguish gold from fool’s gold in the mines of the soul. John warns us that the time may come when “our heart condemns us” unfairly (1 John 3:19) — and the hearts of some, due to a more broken psychology, condemn more often.

Sinclair Ferguson writes,

An individual may have strong faith, much grace, and rich evidence of fruitful service yet lack full assurance because of natural temperament. We are, after all, physico-psychical unities. A melancholic disposition de facto creates obstacles to the enjoyment of assurance — partly because it creates obstacles to the enjoyment of everything. (The Whole Christ, 219)

Or to paraphrase the Puritan Thomas Brooks (1608–1680), if the eyes of the soul wear dark-tinted glasses, then even the sun may seem black.

Means of Assurance

Such are the enemies to a settled, joyful Christian assurance. But great as they are, “he who is in you is greater” (1 John 4:4). God will not allow Satan, sin, and fallen psychology to thwart the possibility of assurance. And so, he offers, through the ministry of his Spirit, means by which we can overcome their assault and “draw near [to God] with a true heart in full assurance of faith” (Hebrews 10:22). And in his providence, his three great means counter our three great enemies: promises defeat Satan’s accusations, Christlikeness overcomes sin’s darkness, and the Spirit’s witness silences our broken psychology.

Promises

To counter the accusations of the devil, God gives “his precious and very great promises” (2 Peter 1:4), and especially those promises that pledge his patience, kindness, and favor toward us in Christ.

J.I. Packer (1926–2020), in one of his books, notes the inconspicuous but crucial for connecting Romans 5:5 and 5:6. In the former verse, Paul offers a picture of warm-hearted assurance: “Hope does not put us to shame, because God’s love has been poured into our hearts through the Holy Spirit who has been given to us.” We might assume such a heart-pouring happens unaccountably, perhaps even mystically. Not so. In the next verse, Paul’s little for draws us to the Spirit’s fountain: “For while we were still weak, at the right time Christ died for the ungodly” (Romans 5:6). In other words, God’s love enters the hearts of those whose minds are fixed on Calvary.

“Assurance is, first and chiefly, the fruit of beholding Christ and the promises he holds out to us.”

Paul takes the same road later in Romans 8, where he sets the “charge against God’s elect” next to the death, resurrection, ascension, and intercession of Christ (Romans 8:33–34) — implying that, in the court of the soul, the devil’s accusations die only when we rest our case on the person, work, and promises of our everlasting Advocate.

Assurance is, first and chiefly, the fruit of beholding Christ and the promises he holds out to us with nail-pierced hands. So, as Brooks says, “Let thy eye and heart, first, most, and last, be fixed upon Christ, then will assurance bed and board with thee” (The Quest for Full Assurance, 127).

Christlikeness

Then, without taking our eye and heart from Christ, the Spirit also nurtures our obedience. As he unveils the glory of Christ, he transforms us “into the same image from degree of glory to another” (2 Corinthians 3:18). He makes us a little garden of grace, where the fruits of Christlikeness take root and grow (Galatians 5:22–23). He also puts a helmet on our head and a sword in our hands to do battle with the un-Christlike “deeds of the body” (Romans 8:13).

As we walk by his power — looking to Christ, becoming like Christ, and confessing our failures along the way — the Spirit assures us that, indeed, “the old has passed away; behold, the new has come” (2 Corinthians 5:17). Christlikeness may grow slowly; it usually does. We also may struggle in different seasons to discern genuine spiritual fruit amid the thorns of our indwelling sin. But the same Spirit who grows his grace inside us can train us also to recognize it. As Thomas Goodwin (1600–1680) writes, the Spirit “writes first all graces in us, and then teaches us to read his handwriting” (Quest for Full Assurance, 137).

Embracing obedience as a means of assurance does not require obsessive introspection — in fact, obsessive introspection usually does more to stifle grace than grow it. In general, grace grows best when no one’s watching, including you. And so, like Paul, we forget what lies behind and strain forward to what lies ahead, keeping our eyes on the Gracious one all the while (Philippians 3:13–14). And then, occasionally, an inward look at our hearts and an outward glance at our lives (perhaps with a pastor or trusted brother or sister) can show us what the Spirit has done.

Witness of the Spirit

The third enemy to Christian assurance, our own broken psychology, likewise finds its match in the ministry of the Spirit, and particularly in what Paul calls the Spirit’s “witness”:

You did not receive the spirit of slavery to fall back into fear, but you have received the Spirit of adoption as sons, by whom we cry, “Abba! Father!” The Spirit himself bears witness with our spirit that we are children of God. (Romans 8:15–16)

Much debate surrounds Paul’s words about the Spirit’s witness. But this much we can say with confidence: Assurance does not ultimately depend on your background, personality, conscience, or common temptations. Rather, assurance depends on the gracious witness of the Spirit, who not only shows us Christ, and not only makes us holy, but who also silences all objections and testifies, “Here is a child of God.” And so, as J.C. Ryle writes, assurance “is a positive gift of the Holy Ghost, bestowed without reference to men’s bodily frames or constitutions” (Holiness, 128).

The Holy Spirit “knows our frame” (Psalm 103:14) — the human frame in general, and our frame in particular. And whatever our psychological makeup, he knows how to communicate his own witness in ways we can hear. He may do so in one dramatic moment, as we read a specific promise or hear the gospel preached. Or he may do so gradually, even almost insensibly, through daily meditation and obedience pursued over years. But no matter how strong the walls, the Spirit can break into the city of our doubts and, where insecurity reigned before, enthrone assurance in its place. So why not ask him?

Preciousness of Assurance

The pursuit of assurance may last long. We may find, moreover, that doubt can return after a long season of confidence, for assurance once enjoyed does not mean assurance always enjoyed. Our peace can rise and fall, requiring a fresh pursuit of assurance through the means God has provided. But however long we have to travel this road, and however often, remember: the preciousness of assurance outweighs all the world.

Who tastes more of heaven on earth than those who walk, freely and happily, through that holy city of assurance, marveling at the heights of Romans 8:31–39? To know with Spirit-given confidence, and not just a frail wish, that the Almighty God is for us, that he gave up his Son to save us, that the blood of Jesus covers us and his intercession upholds us, that neither devils nor conscience can condemn us, and that his love will never leave us — to know all this is to walk, right now, on streets of gold.

Assurance, Ryle writes, enables a man to “always feel that he has something solid beneath his feet and something firm under his hands — a sure friend by the way, and a sure home at the end” (Holiness, 139). Yes, a sure friend, Jesus, and a sure home, heaven: such is the precious gift of assurance — a gift, let it be remembered, that God delights to give.