The biblical teaching on the assurance of grace and salvation is vitally important for healthy Christian living. The provisions that believers are given in Christ are transformative. “If anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come” (2 Corinthians 5:17). The sorting and working out of your new life in Christ will be greatly helped to the degree that you are confident that you have a saving relationship with Jesus.
By assurance we mean a God-given confidence that you are in saving relationship to Jesus Christ. How well you progress in your Christian life will, to a large degree, depend on how confident you are that you are saved. The strength and quality of your confidence depends on how properly grounded your confidence is.
The Bible gives much instruction on this very practical and important subject. One whole book in the New Testament was written for the expressed purpose of helping believers come to a settled assurance of their saving relationship to God through Jesus Christ.
1 John 5:13 says, “These things have I written to you who believe in the name of the Son of God, that you may know that you have eternal life.” “These things” refers back to the whole letter that he had written. John is saying that he has written this small letter to believers for the purpose of helping them have assurance. Since God dedicated a whole book in the Bible for this purpose, it stands to reason that every believer should seek to understand and obtain genuine assurance of salvation.
Such a quest is not without its challenges largely because of two spiritual realities. First, it is possible for an unbeliever to profess to have faith in Christ and to engage in many spiritual activities while remaining unconverted. Jesus warns of this condition in the most sobering words that he ever spoke. “Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. On that day many will say to me, ‘Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?’ And then will I declare to them, ‘I never knew you; depart from me, you workers of lawlessness.’”
These people are gospel hypocrites. They profess Christ but do not possess him. Their faith is not real. It does not rest in Jesus alone. Even though they are zealous and industrious in their religious activities, Jesus warns that they will hear him cast them away because he “never” knew them. Despite their religious profession they continued to give themselves to “lawlessness,” indicating that they never had a saving knowledge of Christ.
Assurance is not only possible, it is vital to Christian health.
Not only is it possible for an unbeliever to look like a believer in many respects but it is also possible for a real believer to look like an unbeliever at many points. This presents a second challenge to understanding and pursuing biblical assurance. For those many months when David committed adultery with Bathsheba, had her husband, Uriah, killed and then lived in impenitence thinking he had successfully managed his sin, he did not look like a man who had a saving relationship with the Lord. Yet, as his later repentance demonstrated (2 Samuel 12:1-15; Psalm 51), he did.
The same could be said of Peter as he denied even knowing Jesus on the night Jesus was arrested. When he and Barnabas became intimidated in Antioch by men who had come from Jerusalem, they fell into hypocrisy; “their conduct was not in step with the truth of the gospel” (Galatians 2:14). By giving into ethnic prejudice, they were acting like unbelievers.
Paul’s revelation of his own internal struggle in Romans 7:13-25 also suggests how difficult it can be for a believer to come to a settled assurance of salvation. “I do not do what I want, but I do the very thing that I hate…I do not do the good I want, but the evil I do not want is what I keep on doing” (Romans 7:15, 19). The internal struggle with the sin that remained in his life as a believer caused him to assess himself to be a “wretched man” (Romans 7:24). The reality of remaining sin, if not rightly understood, can inhibit a proper appreciation of assurance.
Despite these challenges, the Bible does teach that assurance is not only possible, it is vital to Christian health. Every believer is obligated to pursue it. After admonishing his readers to cultivate Christian virtues Peter writes, “Therefore, brothers, be all the more diligent to make your calling and election sure, for if you practice these qualities you will never fall” (2 Peter 1:10).
Three Ways God Gives Assurance
How, then, does assurance work? The Bible teaches three ways that God provides assurance to believers. These interact with and support each other much like the strands in a threefold cord. Together, they can provide full assurance to the believer.
Promises inherent in the gospel
The first means by which God grants assurance to believers is through the promises of salvation that he makes in Scripture. As these promises accompany the very essence of the gospel, when the gospel is truly believed that which it promises is to be received, as well. For example, John 3:36 says, “Whoever believes in the Son has eternal life; whoever does not obey the Son shall not see life, but the wrath of God remains on him.” All who believe in Christ actually possess eternal life. The gospel promises this and, while it is possible to find this promise hard to believe at times (given our sinfulness, inconsistency, and awareness that by nature we actually deserve God’s wrath), it is nevertheless true. In this sense assurance is of the essence of saving faith.
As the Second London Baptist Confession of Faith wisely notes, however, “infallible assurance is not so joined to the essence of faith that it is an automatic and inevitable experience.” The key word in this sentence is “so.” In other words, it is possible for a genuine believer to struggle over the question of assurance, even though the gospel guarantees eternal life to those who believe it.
Evidence of a Spirit-changed life
As mentioned, that is why the Apostle John wrote the first of his New Testament letters. In it, he provides us the second way that God grants assurance of salvation to believers. A careful reading of this letter can help those who believe but who struggle to be certain that they have eternal life. This makes 1 John an essential book for those who are seeking assurance of salvation.
John includes within his little letter a series of tests that an individual can take in order to examine himself and see, as the Apostle Paul admonishes, if he is genuinely in the faith (2 Corinthians 13:5). John focuses on the character and conduct that saving faith produces in the life of a believer. Where spiritual fruit exists, spiritual roots exist.
The apostle does this by writing several “if/then” statements. For example, in 1:6 he states, “If we say we have fellowship with him while we walk in darkness, we lie and do not practice the truth.” Here we learn that if one’s claim to have fellowship with Christ is aligned with a lifestyle that is given over to spiritual and moral darkness, then his profession is a lie. That is, he has no reason to hope that he is a Christian.
Similarly, “And by this we know that we have come to know him, if we keep his commandments. Whoever says ‘I know him’ but does not keep his commandments is a liar, and the truth is not in him, but whoever keeps his word, in him truly the love of God is perfected. By this we may know that we are in him: whoever says he abides in him ought to walk in the same way in which he walked” (1 John 2:3-6). Again, John teaches that profession of faith without an orientation of life toward obedience to God’s commandments demonstrates spiritual deception. Conversely, when we actively seek to follow Christ—to “walk in the same way in which he walked”—then “we may know that we are in him.”
Internal Witness of the Spirit
Along with the promises that are inherent in the gospel and instruction about changed character and conduct, Scripture teaches that the internal witness of the Holy Spirit provides assurance of salvation to believers. Paul writes, “The Spirit himself bears witness with our spirit that we are children of God” (Romans 8:16). This indicates that, ultimately, it is the direct, personal ministry of the indwelling Spirit that assures believers of their place in the family of God.
The Spirit gives assurance. Because this is true, well-meaning pastors and other counselors must be very careful not to usurp the Spirit’s role in the appropriate effort to help struggling Christians come to full assurance. We can, and should, help them to understand the nature of the gospel promises and show how they apply to all who have faith—no matter how small or weak that faith may be—that is grounded in the person and work of Christ. We must also encourage them to understand that, as Luther taught, it is faith alone that justifies. But the faith that justifies never remains alone. It always gives rise to character and conduct that is devoted to godliness.
Along with these efforts, we should encourage every Christian to pray intimately to the Lord, asking for grace to lay hold of the promises inherent in the gospel with an unwavering faith. Such confidence is both possible and commendable. While it is not uncommon for a believer’s assurance to be stronger or weaker at different seasons of life, it should be the aspiration of every Christian to grow in assurance without falling into presumption.
All Three Ways are Vital
It is crucial that all three lines of biblical teaching on assurance be incorporated into one’s thinking and self-evaluation. To pursue only one of the three without the other two will end in spiritual disaster. To rely on the witness of the Spirit without marks of holiness and the promises of the gospel is to get mired in subjectivism that is prone to delusion. To rely on the promises without the Spirit’s witness or the marks of grace is to fall into easy-believism that leads to antinomianism. To rely only on the marks of holiness, however, is to fall into legalism.
By integrating and applying these three areas of instruction on assurance one can profitably pursue a quest for a full and growing assurance of being right with God. Such is the responsibility of every Christian and such is also our privilege.
 Chapter 18, paragraph 3. Emphasis added.