1. Christian Certainties

Introduction to First John

‘These things were written…that you might know that you have eternal life’ (1 John 5:13). John identifies his purpose in writing his first epistle. This is one book of the Bible where we don’t need to guess why. It was written that we ‘might know.’ He writes that we might have confidence in the face of eternity. He establishes the certainties of the Christian religion, those things about which we can be assured. John and, for that matter, the whole Bible encourage believers to be confident of their salvation. We are not meant to face death and eternity as the great unknown, or with consequent doubts and fears. John explains the same purpose in his gospel: ‘but these have been written that you may believe that Jesus is the Christ, the Son of God; and that believing you may have life in His name’ (John 20:31).

We can be assured of our salvation, of the forgiveness of our sins and reconciliation with God, of perpetual and unending life with God after death and in eternity, because of Christian certainties grounded on the life, ministry, death, and resurrection of Jesus Christ, the Son of God, the God/Man, even God the Son.

His method of teaching is by way of contrast. He not only identifies what we know to be true, but he contrasts truth with error. He describes that which is the opposite of the truth which we know. Repeatedly we will hear him say, ‘If we say’ or ‘the one who says’ (1:6, 8, 10; 2:4, 6, 9, 11), or a similar formula (e.g. 2:19, 22, 23; 3:4, 8, 9, 15, 17; 4:3, 8, 20; 5:10, 12, 18) by which to express error and contrast it with the truth. He explicitly identifies false forms of Christianity. This method offends some modern sensibilities. Some would want to know why he (and we) can’t be content just to affirm what we believe and not be critical of others. The reason is, our understanding of truth is sharpened as we contrast it with error. We can be confident of these critical, eternal matters, he says, over against the claims of false religions, of false Christianities, and false Christs, so long as our confidence is in Christian certainties and not a counterfeit. One is reminded of the method of ‘affirmations and denials,’ sometimes used in writing creeds or political platforms, to clarify exactly what is meant and not meant. ‘We affirm that we mean this,’ and ‘we deny by this that we mean that.’ It is to identify and express our certainties, as well as uncover and expose their contraries, that the John writes.


The Apostle John is believed to be the author of this first epistle to bear his name. The author is not identified, but his eyewitness claims (e.g. 1:1–3; 4:14; 5:6), his authoritative, apostolic tone, the epistle’s common subject matter with the fourth Gospel and the other two epistles which bear his name, among other reasons, have led most of the church in most of its history to attribute its authorship to John. Indeed, this was the view of the whole Christian tradition prior to the nineteenth century. A scholar of a previous generation, the great B. F. Westcott (1825–1901), argued respecting 1 John and the Gospel of John, that ‘The writing is so closely connected with the Fourth Gospel in vocabulary, style, thought, scope, that the two books cannot but be regarded as works of the same author.’ Second Edition (Cambridge & London: MacMillan and Co., 1886). The unanimous early Christian tradition that ascribed 1 John to the Apostle John ‘does seem to be the fairest way to read the evidence,’ confirms C.G. Kruse in his recent commentary. (Grand Rapids, Michigan: William B. Eerdmans Publishing Co., 2000), 14.


John writes, late in the first century, to churches probably located in the area of Ephesus, that were being unsettled by an early form of gnosticism. The word ‘gnostic’ comes from the word for ‘knowledge.’ These proto-gnostics held a dualistic worldview. They believed that the world of ideas and the spirit was good, but the physical world was somewhere on the spectrum from evil to harmful to unimportant to unreal. Consequently, they made theological errors: they denied the incarnation by distinguishing between the human Jesus and the divine ‘Christ’ who came upon Jesus at His baptism and departed before the suffering of the cross. Church historians recognize this as an early form of Docetism. Christ only seemed to suffer, they argued. Jesus suffered, but Christ did not. Consequently, salvation for them came not through the death of Christ, but through knowledge, especially knowledge of mysteries and secrets revealed through special rituals and ceremonies.

As is always the case, theological errors lead to moral errors. Their depreciation of the physical led, on the one hand, to an extreme asceticism, denying the body its appetites for the sake of spiritual enlightenment; and, on the other hand, to an extreme carnality, denying the relevance of anything the body did. John Stott explains that, ‘The better Gnostic systems combined these views of spiritual enlightenment and release with a strict asceticism; the worst systems asserted that evil could not harm the enlightened spirit, and that the grossest forms of license were quite permissible.’, Tyndale New Testament Commentaries (1964, Grand Rapids, Michigan: William B. Eerdmans Publishing Co., 1975), 46. Furthermore, this exaltation of knowledge led to social errors, to pride, elitism, and an unloving spirit.


The result of all this was to disrupt and unsettle the church. Many of these early Christians were confused and uncertain. Some of the false teachers had left the church. ‘They went out from us,’ John says (2:19). C. G. Kruse refers to them as the ‘secessionists.’ This disrupted the church. Some were tempted to leave and go with them. Others, such as Diatrophies, ‘who loves to be first’ (3 John 9), remained and continued to sow discord and confusion. The Apostle John’s strategy, then, is to remind his readers of what they already know, and the things about which they (and we) can be certain. Forty times he uses the words ‘to know’ (ginoskw, eideo); 25 times he uses the word ‘confidence’ or ‘boldness’ (parresia). He is concerned to establish Christian certainties. James Boice identifies ‘Christian assurance’ as the ‘dominant theme’ of the epistle.’ (Grand Rapids, Michigan: The Zondervan Corporation, 1979), 9. John’s letter is what the NEB calls a ‘Recall to Fundamentals,’ and outlines true Christianity while distinguishing it from counterfeits. His aim is to lead his readers ‘to a deeper understanding of the faith and to confidence in what they already possess,’ says Boice. (Grand Rapids, Michigan: The Zondervan Corporation, 1979), 9, 12. Simply, ‘John’s ultimate aim in his first Epistle,’ says the British New Testament scholar, I. H. Marshall, ‘is to give his readers solid grounds for assurance that they have eternal life through belief in Jesus Christ.’ ‘Here are the marks of true Christianity,’ he says, and conversely, ‘here are the marks of liars and deceivers and the antichrist.’

There is hardly a more relevant book for the Christian church today. Our age denies that one can know anything with certainty, especially in the area of religion. Those who think they do know are seen as arrogant and unrealistic. ‘How can you say that you have the truth when so many good people see it differently?’ The Christian church can be intimidated by moral and religious relativism into saying nothing. We are awash as well in a new age spirituality which is divorced from the physical world and moral categories much like first century Gnosticism. Moreover, many Christians struggle with personal assurance. They believe the Christian certainties. But they doubt if those certainties apply to them. They wonder if they truly believe. They wonder if they might just be hypocrites or counterfeits. John says we can know the true religion, and we can know the signs by which to identify those who possess it. He uses three basic tests by which to discern genuine Christianity and the genuine Christian: the moral, the theological, and the social. (Edinburgh: The Banner of Truth Trust, 2008). These tests recur repeatedly, almost randomly, through the entire epistle.

Theological test

According to the Apostle John, it matters what we believe. We’ve heard the claim, ‘God isn’t concerned with doctrine or creeds. He doesn’t care about theology or religious differences. He cares about how we act. Care not about creeds; love not doctrine.’ These sentiments sound open-minded and charitable, but they are not the thoughts of biblical religion. John deals harshly with those who deny the full humanity and divinity of Christ, calling them liars and antichrists and deceivers (e.g. 1:6, 10; 2:4, 18, 22; 3:8; 4:1–3, 6, 20; 5:10–20): ‘Who is the liar but the one who denies that Jesus is the Christ? This is the antichrist, the one who denies the Father and the Son’ (1 John 2:22). They cannot be considered Christians if they separate Jesus from the Christ, and in so doing, deny the incarnation: ‘Whoever denies the Son does not have the Father; the one who confesses the Son has the Father also’ (1 John 2:23). The answer is for them to ‘abide’ in that ‘which you heard from the beginning.’ Revealed religion doesn’t change. It is not subject to alteration or improvement: ‘As for you, let that abide in you which you heard from the beginning. If what you heard from the beginning abides in you, you also will abide in the Son and in the Father’ (1 John 2:24). Again he says,

Beloved, do not believe every spirit, but test the spirits to see whether they are from God; because many false prophets have gone out into the world. By this you know the Spirit of God: every spirit that confesses that Jesus Christ has come in the flesh is from God; and every spirit that does not confess Jesus is not from God; and this is the spirit of the antichrist, of which you have heard that it is coming, and now it is already in the world. (1 John 4:1–3)

Religious differences cannot be reduced merely to differences of opinion. The ‘spirits’ must be ‘tested.’ There are ‘false prophets.’ There is the spirit that comes from God and that which is ‘the spirit of antichrist.’ And again:

We are from God; he who knows God listens to us; he who is not from God does not listen to us. By this we know the spirit of truth and the spirit of error. (1 John 4:6)

The one who believes in the Son of God has the witness in himself; the one who does not believe God has made Him a liar, because he has not believed in the witness that God has borne concerning His Son. And the witness is this, that God has given us eternal life, and this life is in His Son. He who has the Son has the life; he who does not have the Son of God does not have the life. (1 John 5:10–12)

For John the categories are quite clear cut and absolute. There is truth and error, true prophets and false prophets, life and death, Christ and antichrist. Real Christianity and real Christians confess the truth about Christ.

There are certain doctrines which must be believed in order to be truly Christian. They are not new or novel doctrines, but those which have been believed from the beginning about the dual nature of Christ, His humanity and divinity, His pre-existence and incarnation.

One reason why we recite the Apostles’ or Nicene Creeds each week in our public services is that by doing so we join hands with the great mainstream of Christendom. The doctrines of the Creed are those which Christians have believed ‘from the beginning’ (1:1–3; 2:24). The creeds summarize the historic Christian faith. Through them we identify ourselves with the church militant and triumphant, with the ‘holy catholic church.’ We are not a sectarian group. We are not a heretical aberration. We are not a cult. The sure sign of the cult is departure from this doctrinal mainstream, particularly as it relates to the person and work of Christ. This is why the Jehovah’s Witnesses, the Moonies, Christian Science, Divine Light Mission, and scores of others are not Christian. They fail the doctrinal test. They either deny the humanity of Christ or the divinity of Christ. They deny the reality of sin and judgment. They fail, and so they cannot but be the spirit of error, a deception, the antichrist, false prophets, and liars. ‘Right belief is not a theological nicety,’ says Ian Hamilton, ‘it is necessary for salvation.’

We must be of sound doctrine if we are to be truly Christian. This is how we first distinguish the true from the false. Are they orthodox? Am I orthodox? Do I believe as the Bible teaches and what Christians have always believed about Christ? If so, then I may assure my heart that I am a true Christian.

Moral test

True religion will always issue in righteousness. Where true Christianity is present, there will be recognition of the holiness of God, the sinfulness of man, and the need of a Savior. Christ will be received as Savior, and in so doing one’s life will be transformed. It is not possible to combine truth and moral laxity. This is John’s second major thrust. He says the message of the gospel begins with the affirmation that ‘God is light’ (1:5). The same Apostle who repeatedly tells us that ‘God is love’ (4:8) also says that ‘God is light.’ Light represents both truth (the light of truth) and holiness (the light of purity). ‘In him there is no darkness at all.’ This needs to be said over and over again. Yes, God is love. But He is also light, and therefore imminently concerned with truth and holiness. He is a righteous God. Don’t allow His love to obscure this. Don’t be fooled into thinking that because God is love, He is therefore indulgent of evil. God is not soft on sin. God will not wink at sin. God does not forgive sin ‘no matter what,’ regardless of what we do or how we respond. This is a pernicious half-truth at best. The God who is love is light. His children are necessarily children of light. Their lives are like His life, holy as he is holy. One cannot live a life of promiscuity and moral degradation and rightly claim to be a Christian. John’s language is strong. A Christian will walk in the light!

If we say that we have fellowship with Him and yet walk in the darkness, we lie and do not practice the truth; but if we walk in the light as He Himself is in the light, we have fellowship with one another, and the blood of Jesus His Son cleanses us from all sin. (1 John 1:6–7)

A Christian will recognize that he is a sinner and confess his sin. The Light will show him that.

If we say that we have no sin, we are deceiving ourselves, and the truth is not in us. If we confess our sins, He is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness. If we say that we have not sinned, we make Him a liar, and His word is not in us. (1 John 1:8–10)

A Christian will keep the commandments.

The one who says, ‘I have come to know Him,’ and does not keep His commandments, is a liar, and the truth is not in him; but whoever keeps His word, in him the love of God has truly been perfected. By this we know that we are in Him: the one who says he abides in Him ought himself to walk in the same manner as He walked. (1 John 2:4–6)

Right doctrine will result in right practice. I attended college with a fellow who believed all the evangelical doctrines. He said he had faith in Jesus Christ. He said Jesus was His personal Savior. He also said there was nothing wrong with fornication. His moral life was a cesspool. John would say this is a deception. One cannot be a Christian and habitually practice immorality. True Christianity is incompatible with habitual carnality. There must be spiritual transformation and moral reformation. There must be a recognition of sin, and repentance from sin.

The moral test is being compromised today by two very different groups. First, there are the liberals, whole denominations of whom are rewriting God’s commandments to accommodate the ways of life condemned by God in His word. To advocate the normalizing of extra-marital sexual conduct in all its forms: fornication, homosexuality, serial divorce, and polygamy, is to fail the moral test.

The second group is the evangelicals, so many of whom, due to ‘market’ considerations, do not want to hear about or preach about sin. They don’t want to be negative. They want to only uplift and encourage. There is more than one way to say ‘we have no sin.’ The liberals redefine sin so as to accommodate the behavioral choices of privileged groups. Evangelicals simply quit talking about it, instead majoring on the helpful messages on marriage, child-rearing, finances, and self-esteem. It’s no wonder that whole congregations feel like the preacher is ‘beating up on them’ if sin is ever mentioned, and get depressed if they are told to die to their selves, practice self denial, and obey God’s commands. This, too, is to fail the moral test.

John grounds assurance in obedience: walking the light, confessing our sins, and keeping the commandments. ‘If we walk in the light…the blood of Jesus cleanses us from all sin’ (1:7). Again, ‘if we confess our sins’ God will ‘forgive us our sins and cleanse us from all unrighteousness’ (1:9). Again he says: ‘And by this we know that we have come to know Him, if we keep His commandments’ (1 John 2:3). The true Christian obeys the commandments of God. Not perfectly, of course, but characteristically. Not sinlessly, but earnestly and sincerely. The true believer is committed to obedience and the practice of obedience. If we have a sincere desire to obey God, and if we are growing in obedience, we are to be assured that God is at work and our faith is authentic.

‘God’s self-revelation is ethical,’ says John Stott, ‘and there can be no fellowship with Him without righteousness.’ But where transformation has taken place, where the fruit of salvation has been obedience and holiness, we can be assured that our Christianity is authentic, and be assured of our salvation.

Social test

The final test of true Christianity is that of love. He touches on the ‘new commandment’ in 2:7–11. Then he explains more fully in 4:7–8: ‘Beloved, let us love one another, for love is from God; and everyone who loves is born of God and knows God. The one who does not love does not know God, for God is love.’ For Augustine, the First Epistle of John is ‘very sweet to every healthy Christian heart that savors the bread of God,’ because ‘what it specially commends to us is love.’, Vol. 11 (Downers Grove, IL: InterVarsity Press, 2000), 166, from his Ten Homilies on 1 John, Prologue. Knowledge of the God who is love transforms us into a people of love. John tells us, ‘We love, because He first loved us’ (1 John 4:19). God’s love for us inspires our love for others. If we know that love it will generate love in us. God’s love for us produces love for others. Jesus teaches us to love everybody, even our enemies (Matt. 5:44). But John is particularly concerned with love for fellow Christians, for the brethren.

By love, John means more than warm feelings, though warm feelings ought to be present too. He wants to see tangible, costly sacrifice. He asks,

We know love by this, that He laid down His life for us; and we ought to lay down our lives for the brethren. But whoever has the world’s goods, and beholds his brother in need and closes his heart against him, how does the love of God abide in him? Little children, let us not love with word or with tongue, but in deed and truth. (1 John 3:16–18)

Love means sacrifice. Love means costly service. Love means we ‘lay down our lives for the brethren.’ He says again, ‘We shall know by this that we are of the truth…’ (3:19). Love of my fellow Christian ‘in deed and truth’ is a sign of authentic Christianity.

Conversely, the one who does not love cannot be a genuine Christian. The real Christian does not harbor hate in his heart for fellow believers. Again, ‘If someone says, “I love God, ” and hates his brother, he is a liar; for the one who does not love his brother whom he has seen, cannot love God whom he has not seen’ (1 John 4:20). Love for God cannot coexist with hate for the brethren. True love for God will not indulge animosity in our hearts for fellow Christians. We cannot be content to let bitterness remain within. We must pray it out. We must crucify it.

In a true Christian community, awareness of needs leads inexorably to the meeting of those needs. Is one lonely? Then as others become aware of this they will see to it that he is befriended. Is one in financial need? Then others will do what they can to help with that need. Is one sad? Is one hungry? Is one in trouble with the law? Is the family falling apart? Is the marriage hurting? In the true church, there is a bearing of the burdens of one another (Gal. 6:2). We cannot say we love God whom we cannot see, and yet not love his children whom we do see (4:20).

The founding pastor of the Massachusetts Bay Colony, John Cotton (1585–1652), said that the Apostle John, under the inspiration of the Holy Spirit, ‘penned this epistle for pacifying our consciences with the peace of God and filling our hearts with joy in the Holy Ghost (1:4).’ (1657, Lafayette, IN: Sovereign Grace Publishers, 2001), 5. Remember, the Apostle John gives us the reason for his writing this epistle in 5:13: ‘These things I have written to you who believe in the name of the Son of God, in order that you may know that you have eternal life.’ He writes to those who ‘believe in the name of the Son of God.’ He writes to us who identify ourselves as Christians. ‘In order that you may know that you have eternal life.’ How are we to know? How are we to be sure? He gives us these tests. Do we believe in Jesus Christ as the Son of God and God the Son? Do we hold to the historic Christian doctrines? Can we say the Apostles’ Creed and mean it? This is the doctrinal test.Do we walk in the light? Do we keep the commandments? This is the moral test.

Finally, do we love the brethren? Do we love them in deed and truth (3:18)? This is the social test. Those who are born of God believe, they obey, and they love. Is this us? If so, then we may rejoice in the work God is doing in our lives. If not, then something is wrong, something that must be made right. These tests in 1 John are how the true is distinguished from the false. True Christianity is rooted in Christian certainties and can be seen by its fruit. Where we see these things in combination, faith, obedience, and love, there is true religion, the true church, and the true believer.