True faith is assurance of personal salvation. Because assurance is certainty—absolute certainty (to be redundant)—true faith is certainty of one’s own salvation. It is certainty of deliverance from sin, death, and hell. It is certainty of acceptance into the fellowship of God, which is life eternal. Faith is assurance of salvation by the blood and Spirit of Jesus Christ according to the electing love of God in eternity.

True faith is assurance.

Assurance is not the fruit of faith. Assurance is not the reward of faith. Assurance is not a branch or appendix of faith. Assurance is not a later, heroic, rather rare development of faith, after many years of faith’s struggling with doubt and working to attain to assurance.

Assurance is what faith is.

Assurance is of the very essence of faith.

Strip faith of assurance (to speak nonsense), and what is left is not faith. What is left is unbelief.

Believers can sinfully doubt their salvation. But this doubt is not inherent in their faith. Doubt is not an unfortunate aspect of the faith of most Christians for much of their lives. Doubt is not 75% of faith along with 25% assurance, or even 1% of faith along with 99% assurance, until finally, for a few of “God’s best and dearest friends,” faith becomes 100% (full) assurance. Doubt is not even an evil that faith placidly puts up with day after day, year after year, generation after generation, as the normal way of life of the believer.

Doubt of one’s own salvation for a believer has its source in the Christian’s depraved, unbelieving nature. The spiritual father and nourisher of doubt is Satan. He created doubt in the beginning: “Yea, hath God said?” Doubt is sin. Undoubtedly, if we judge our sins rightly, as God judges them, the sin of doubting our salvation is more heinous than adultery, or stealing, or murder, or the other gross fleshly iniquities. What are these sins in comparison with making God a liar in His promises to us, or in comparison with accounting the suffering and death of the Son of God inadequate to redeem and forgive us?

Faith has nothing to do with doubt, except to condemn it, fight it, and overcome it.

Biblical Definition

Holy Scripture defines faith as assurance of salvation in Hebrews 11:1: “Now faith is the substance of things hoped for, the evidence of things not seen.” The word translated “substance” in the Authorized Version means “firm confidence,” or “assurance.” Luther correctly translated the word as “eine gewisse Zuversicht,” that is, “a certain confidence.” Faith is assurance that the things the believer hopes for, according to the promise of the gospel, are both real and for him personally. Similarly, faith is the “evidence,” that is, the conviction, that the things not seen are realities for the believer. Since the things hoped for and the things not seen are the things of salvation in Jesus Christ, faith is the assurance and conviction of salvation.

Assurance of salvation is what faith is.

That the apostle refers to the believer’s assurance and conviction of his own personal salvation is put beyond doubt by verse 2: “For by it the elders obtained a good report.” By faith the believer obtains a good report, obviously, about himself.

Certainty in the “Union” Texts

All the innumerable passages in Scripture that describe faith as union with Christ, so that the one who has faith is “in Christ” and Christ is in the one who has faith, teach that faith is assurance of belonging to Christ. Such a passage is Ephesians 3:17: “That Christ may dwell in your hearts by faith.” Faith receives Christ in the heart of the believer. The one in whom Christ dwells knows the love of Christ—knows the love of Christ for himself (v. 19). Union with Christ, which is faith, is certainty of this Christ. Union with Christ—with Christ—cannot but be certainty of this Christ for oneself. Union with Christ is as much certainty that Christ is one’s own as the marital union is a woman’s certainty that the man to whom she is united is her husband. Who would teach that a woman—a Christian woman—can be married to a man—a godly man—but live in perpetual doubt whether he is her husband.

“Assurance of Faith”

Several passages of Scripture explicitly attribute assurance to faith. In previous articles in this series, I have already quoted and explained Hebrews 10:22: “Let us draw near with a true heart in full assurance of faith.” “Full assurance” in the translation of the Authorized Version is simply “assurance,” which in the nature of the case is always “full.” This assurance of faith is not certainty that the believer has faith. But it is the certainty that belongs to faith, indeed, the certainty that is of faith’s essence. It is faith’s certainty that, washed with the blood of Jesus, his own Savior, the believer may boldly draw near to God Himself as his God. It is certainty of salvation.

“By the term full assurance,” Calvin explains, “the Apostle points out the nature of faith, and at the same time reminds us, that the grace of Christ cannot be received except by those who possess a fixed and unhesitating conviction” (commentary on Heb. 10:22).

“I am Persuaded”

The texts that characterize the one who believes the gospel as certain of the love of God for him, certain of the death of Christ for him, certain of the Spirit indwelling him, and certain of his future life and glory are legion. They are glorious. How did the Puritans dare to deny that faith is assurance? How do their spiritual heirs dare to deny this today? On the lips and in the heart of every one who believes the gospel of grace, every one who is “in Christ Jesus” by faith (Rom. 8:1), the apostle puts these sublime words of assurance: “Who shall separate us from the love of Christ? … For I am persuaded that [nothing] … shall be able to separate us from the love of God, which is in Christ Jesus our Lord” (Rom. 8:35-39).

By faith, every believer knows with certainty the love of God in Christ for him. By faith, every believer is persuaded that he will abide in this love forever.

This grand passage in its context in Romans is by itself alone the utter refutation of the notion that assurance does not belong to the essence of faith.

Justifying Faith as Assurance

In a class by themselves, as regards the question whether assurance is of the essence of faith, are the passages that teach justification by faith. Faith justifies. No one supposes that justification is a much later development of faith, or a reward of faith, or an addition to faith, or an appendix to faith. Justification is the fundamental benefit of faith. So soon as one believes, regardless that his faith is weak or strong, God justifies him by means of his faith in Jesus Christ. But justification is the forgiveness of sins, the imputation of Christ’s righteousness, the adoption unto sonship, and the appointment as heir of the world in the consciousness of the justified sinner. “I tell you,” said Christ about the publican, “this man went down to his house justified” (Luke 18:14).

If one hears the verdict of God in his consciousness, “I forgive your sins for the sake of Jesus Christ in whom you trust,” he is certain that God is favorable to him, that Christ died for him, and that he himself personally is saved. Justification involves assurance of salvation. Since justification is the fundamental benefit of faith, faith is assurance.

If now, the advocates of doubt respond that justification is not forgiveness in the forum of one’s consciousness, if they argue that it is possible to be justified without being sure of it, if they contend that, in fact, most Christians have faith and are justified without any certainty that their sins are forgiven, they sin against the basic gospel-truth of justification, as against the testimony of the entire Reformation.

And if they are right, the truth of God’s free justification of sinners leaves me cold. Justification does me no good. It leaves me, believer though I am, groaning in the misery of the guilt and shame of my sins and sinful nature, and fearful of a wrathful God. It sends me home as condemned in my own consciousness as the damned Pharisee.

Of Psalm 23, as the confident confession of every believer, and of the model prayer—the “Our Father”—as the confident prayer of every believer, I have spoken before in this series on assurance.Both of these familiar passages of Scripture are essential elements of the Christian’s life. Both imply certainty of salvation. Both are the expressions of faith. Faith says, “The Lord is my shepherd.” And faith says, “Our Father.” Faith says, “The Lord is my shepherd,” and, “Our Father,” because faith is assurance of salvation.

Assurance by Virtue of the Sure Promise

Faith is essentially and necessarily assurance because of the promise to which faith looks and upon which faith depends. Faith never exists by itself alone. Faith is always trust in the promise of God. The promise creates faith and draws faith to itself. The promise of God is true and certain altogether. Faith is convinced of the promise. Because the promise is God’s sure Word of the salvation of the one to whom the promise is given, and who believes the promise, faith is certainty of salvation.

As certain as is the promise of God, so assured is faith that receives and depends on the promise.

In Romans 4:13ff., the apostle teaches that faith is assurance by virtue of the sure promise that faith has respect to. Abraham “staggered not at the promise of God through unbelief; but was strong in faith, giving glory to God; and being fully persuaded that, what he had promised, he was able also to perform” (vv. 20, 21). What was true of Abraham is true also of every one of us who has the faith of father Abraham (v. 23). Our faith too is “full persuasion” of God’s promise of our salvation in Christ.

So much is God, the heavenly Father of all His sons and daughters, determined that His dear children not live in miserable, terrifying, sinful doubt, that He adds an oath to His promise. “God, willing more abundantly to show unto the heirs of promise the immutability of his counsel, confirmed it by an oath: that by two immutable things, in which it was impossible for God to lie, we might have a strong consolation, who have fled for refuge to lay hold upon the hope set before us” (Heb. 6:17, 18). This implies all the more that faith, which knows and rests on the promise, is assurance.

Preaching Assurance

Believers and their children must be taught that faith is assurance. The Spirit of Christ works assurance of salvation, that is, faith, by the sound, healthy, and health-giving preaching of the Word. Healthy preaching assures the believer that his faith may, must, does, and will consist of certainty of salvation.

Preaching that denies that faith is assurance; preaching that suggests that one can trust in Christ for salvation without having assurance; preaching that reserves assurance for only a few believers, who must make themselves worthy by years of struggle with doubt; preaching that delights in directing the spiritual gaze of men and women who believe the gospel away from Christ crucified to their own experiences, questioning the genuineness of their faith, the sincerity of their sorrow for sin, and the reality of their salvation—sickly preaching—creates doubters. The Spirit of Christ certainly does not make such preaching His means to work assurance, that is, faith, in the congregation.

Good preaching always comes “in much assurance” (I Thess. 1:5).

Not in much doubting.