You hear a knock at the door or a ring at the doorbell. You go outside to see who it is, and standing there are two well-dressed people, with pouches or bags slung over their shoulders. You ask if you can help them and they tell you that they are sharing the good news of the kingdom of God. They have magazines which look well printed, with lots of well-written articles about contemporary issues, and quite a few pictures of Jesus with lions and lambs. You realise these members of a cult that teaches Jesus is the same creature as Michael the archangel, and that salvation is by good works. What do you do? Do you bring them in and talk? Do you buy their magazine to get them off your back? Do you thank them, but tell them you are not interested? Do you fetch a baseball bat and chase them off our street?

John is writing to the elect lady, and he urges her to continue to keep the old commandment – to love one another. Christians love; Christians are to love God with all their heart, soul and mind. Christians are to love one another as Christ loved them. Christians are to love their neighbours as themselves. Christians are even to love their enemies. The aim of God’s commandments to us is love out of a pure heart (1 Tim 1:15).

However, John has been showing that love is limited by truth. Love is not about giving vent to my own self-expression; love is responding to the properties and attributes of the one we love. It is responding to truth about the person we love. If love is a train, then truth is the railway tracks. If love is electricity, then truth is the wire. If love is water, then truth is the vessel. Truth holds, guides and disciplines our love. Truth shapes our love. Apart from truth, our love becomes undisciplined, formless, and eventually, can become idolatrous.

John is telling us something that goes against our views of love. He is telling us that love firstly submits and obeys truth about the Beloved. We tend to be suspicious of submission and obedience and commands and written instruction. But John says – this is your freedom, this is real love, this is what gives love beauty and shape and purpose. Like a sculptor takes a lump of unshaped clay and shapes it, so truth sculpts our love into a beautiful thing.

The reason John is urgent and speaks so strongly is that there is something present in the world that threatens the love itself. Something has entered the world that, if left to have its own way, will actually destroy Christian love. Like termites eating out the bottom of a wooden ship, this thing, if left alone, will mean there is no ship of love to sail.

And it seems that the elect lady is one whose love might be becoming a little undisciplined, a little shapeless, a little sentimental. She might be the kind who feels so sorry for those termites, and feels that they, too, have a right to life, that they are just being termites.

John wants to make it clear that Christian love has a boundary that must be protected. Like the skin of a water balloon, this boundary is what holds and shapes Christian love. If you pierce that skin, the water comes bursting out. If you remove this boundary, Christian love no longer has a shape. If this threat is allowed to have its way, it will punch a hole right through the skin, and there will no longer be a difference between Christian love and the world’s love. There will no longer be a way for Christians to know how to love God, and one another and their neighbours.

We have already seen that this boundary is truth. John is now going to go further, and show us specifically what truth He is going to show us which truths guard Christian love, and how we go about guarding it ourselves.

I. The Boundary of Christianity and its love is the Gospel (v6, 7, 9)

2 John 1:7

For many deceivers have gone out into the world who do not confess Jesus Christ as coming in the flesh. This is a deceiver and an antichrist.

Verse 7 begins with the word ‘for’ which connects it back to verse 6. Verse 7 is an explanation of verse 6. What did verse 6 say?

2 John 1:6

This is love, that we walk according to His commandments. This is the commandment, that as you have heard from the beginning, you should walk in it.

Walk in the commandments, in the truth that you heard from the beginning. Keep yourself in the love of God, as revealed in the written commandments of Scripture. Why? Verse 7 – because there are people about trying to change that old truth that you heard from the beginning. They are coming with something new, and what they have is different to what you heard from the beginning.

When it comes to the gospel, the saying goes, ‘if it’s new, it’s not true, and if it’s true, it’s not new’. John says, you know the truth of Scripture which has been taught and handed down, but now there are some threats. What does John call these people? He gives them two titles. In verse 7, he says, they are ‘deceivers’. The word for deceiver means someone who pretends to be something he isn’t, and so leads people astray. He is an impostor. An impostor is a person who has no right to stand where they do. Recently, a couple in America were caught attending special events and parties that were held for very high-ranking politicians. This couple would dress smartly, look confident, and just enter these parties uninvited. They were impostors. So John says, there are people trying to gain access to Christian churches and Christian homes, and Christian minds who do not belong there. They are not Christians, and they will lead people astray.

The second term John gives for such people is ‘antichrist’. This means someone who opposes Christ while claiming to speak for Christ. He says, “I am on Christ’s side. I love Christ, I speak for Christ”, but he actually is the enemy of Christ. If you listen to him, you will end up opposing Christ.

Now how many of these deceivers and antichrists does John say are around? Verse 7 says, “many”. So, here are Christians who must love, and love in the truth, submitting to what God says and what God is. But, there are now people around who will deceive and oppose so that if you let them in – they will destroy Christianity itself. What is it that they do which makes them deceivers and antichrists? Verse 7 and verse 9 gives us a sample of their teaching:

For many deceivers have gone out into the world who do not confess Jesus Christ as coming in the flesh. Whoever transgresses and does not abide in the doctrine of Christ does not have God.

Let’s unpack that for a moment. If someone believed that Jesus did not truly come in the flesh, what does that mean, and what are its implications? Well, such a person believes Jesus wasn’t really a human being. He was a spirit-being who looked human, like when angels manifested themselves to man. Or perhaps, there was this man Jesus, not born of a virgin, born of two natural parents, and this Christ-Spirit possessed him for several years.

Now what would that teaching mean? If Jesus was just a spirit, then it means He did not actually take on our nature. He did not actually share in our humanity. If Jesus was not truly human, can He be a mediator between God and man? Can he be a true substitute for another human? Can He really be the second Adam? No. If Jesus was not truly human, or if the Christ-Spirit only was with him between his baptism and His crucifixion, then there is no power in the death of Jesus on the cross, and the whole gospel falls to the ground.

What John is saying, is that there are people around who claim to be Christians, but are actually pulling the beating heart out of Christianity. There are people who claim to be Christians, but are short-circuiting the very means of becoming a Christians. A person who claims to be a Christian but denies the gospel, is an apostate. They say they are one thing, but they are actually another. They are trojan horses. In the Aeniad, Virgil talks about the strategy that allowed the Greeks finally to enter the city of Troy and end the conflict. After a 10-year siege, the Greeks constructed a huge wooden horse, and hid a force of 30 men inside. The Greeks pretended to sail away, and the Trojans pulled the horse into their city as a victory trophy. That night the Greek force crept out of the horse and opened the gates for the rest of the Greek army, which had sailed back under cover of night. The Greek army entered and destroyed the city of Troy, decisively ending the war.

Why is this so important? Because the gospel is the boundary of Christianity. A person who believes the gospel, crosses that boundary, and enters the Body of Christ. To believe the gospel is to go from being outside the invisible church, to being in the inside. If you change the gospel, you no longer have Christianity. If you no longer have Christianity, you no longer have Christian love. Love dies. Love is scattered. Love becomes like water when the water balloon is pricked with a pin. Remove, warp, change the Gospel, and the balloon bursts.

We no longer know what it is to be a Christian. We no longer know who is a Christian and who isn’t. We no longer know how to love Christians versus how we love the unsaved. And there is definitely a difference. You love your neighbour as yourself, but you love fellow believers as those you are willing to lay down your life for. But the only way you know who is inside the circle, and who is outside the circle is by knowing what the gospel is.

The truth of the gospel, the old, handed-down commandment to repent and believe in Christ is the boundary of Christianity. Therefore, any attack or perversion on the truth of the gospel, is an attack on the faith itself. It is going for the jugular of Christianity. The most important doctrines in the Bible are those doctrines that are essential to the gospel. They are life support for the whole system of faith. They are not toenails, tonsils or appendices. They are hearts, lungs, brains of the whole thing. They are essentials, fundamentals. We call them fundamental doctrines – teachings essential to the gospel.

Not all doctrine is equally important. Not all teaching must be defended with the same vigour. We judge how important a doctrine is by what it does to the whole system of faith. And to deny something central to the gospel is to deny the faith itself.

When John mentions this heresy, he is not saying that this is the only possible attack on the gospel. He is giving one example – an example that was current in his day. However, there are many ways that a person can deny the gospel. If you deny that Jesus is truly God, like the Jehovah’s Witnesses and Mormons do, you have denied the gospel. If you deny that Jesus is the Son of God, and that He has a Father and has sent the Spirit, i.e., if you deny the Trinity, you are denying the gospel, as the Unitarians do. If you deny that man is actually sinful and needs saving from God’s anger, you have denied the gospel, like Christian Science does. If you deny that Christ rose from the dead, or that there will be a resurrection of both the righteous and the wicked, like liberals do, you have denied the gospel. If you deny that salvation is by grace alone, through faith alone, in Christ alone, you have denied the gospel.

The gospel is that the triune God made man to fellowship with Himself, but man rebelled and fell into sin, of which the penalty is hell. God the Son chose to enter the human race through a virgin birth, lived a sinless life, died as a penal substitute for sinners, rose again, ascended to heaven, and will return. All those who repent of sin and trust in Jesus Christ for forgiveness, and a new life of following Him receive eternal life and will not be condemned.

This is the gospel. At the risk of being misunderstood, this is traditional gospel. It is the gospel that the church has understood from its inception. It is, as John put it, the truth you heard from the beginning. This is why we happily recite the Apostle’s Creed:

We believe in God, the Father Almighty, the Creator of heaven and earth. And in Jesus Christ, His only Son, our Lord: Who was conceived of the Holy Spirit, born of the Virgin Mary, suffered under Pontius Pilate, was crucified, died, and was buried. The third day He arose again from the dead. He ascended into heaven and sits at the right hand of God the Father Almighty, whence He shall come to judge the living and the dead. We believe in the Holy Spirit, the holy universal* church, the communion of saints, the forgiveness of sins, the resurrection of the body, and life everlasting.

The doctrine of Christ, as verse 9 puts it, is essential to the gospel. The person who remains in the teaching of Christ – the gospel-centred essential truth – has both the Father and the Son.

Do you see why John wants us to know that love is rooted in truth? If you do not have the truth of the gospel, its doctrines, its teachings, you do not have the gospel. If you don’t have the gospel, you don’t have Christianity, and then you don’t have love. Christian love is irreducibly doctrinal.

We must have and understand the teachings of the gospel if we are to know the boundary of Christianity – how to get in, who is in, who is out. That’s why before your baptism or membership testimony we ask you not only for a statement of what has happened in your life, but for a brief articulation of the gospel. We’re saying, give us the gospel in your own words.

But there is a strong move in a culture today away from such things. As we said, love is supposed to be spontaneous and free and all about self-expression. When you start drawing lines, and marking a perimeter of the Christian faith, people say, “This isn’t loving! This is spiritual terrorism! This is intolerant! This is narrow-minded bigotry! Who are you to say who loves God and who doesn’t? Who are you to say who is a Christian and who isn’t? Only God knows!” Fair enough, only God knows. But what God tells his church is that the boundary of Christianity is the gospel. At minimum, for someone to be recognised as a Christian, and therefore loved as a brother or sister, he or she must profess the gospel.

II. This Boundary is to Be Respected and Protected

2 John 1:10-11

If anyone comes to you and does not bring this doctrine, do not receive him into your house nor greet him; for he who greets him shares in his evil deeds.

Here is John’s controversial application of the Gospel-as-boundary. He says, if someone comes to you and does not bring the teaching of the true gospel, while claiming to be a Christian, do not let him in and do not greet him. If you do that, you are partaker of his evil works.

Wow. If we thought John’s teaching on love being limited by truth seemed strong, this seems even stronger. Not greet? What happened to Christian courtesy? What happened to common kindness? This goes against the grain of our thoughts about human decency.

Well, let’s unpack this for a bit.

Remember that John is writing to the elect lady and her children. More than likely, this is either a church symbolised by the term ‘lady’, or perhaps a real lady who hosts a church in her home. As we mentioned last week, the Roman world was not the kind of world where it was easy to travel without hospitality. Christians were known for their kind hospitality to one another. In fact 3 John exhorts and encourages just this kind of hospitality.

3 John 1:5-8

Beloved, you do faithfully whatever you do for the brethren and for strangers, who have borne witness of your love before the church. If you send them forward on their journey in a manner worthy of God, you will do well, because they went forth for His name’s sake, taking nothing from the Gentiles. We therefore ought to receive such, that we may become fellow workers for the truth.

Churches were hosted in homes. Travelling preachers and fellow Christians would try to find these homes to lodge in, and possibly preach in. Notice what John says: when a church or a home receives and helps true brethren, they become fellow workers for the truth. When a church extends welcome and recognition to true Christians, it helps and advances the truth.

On the other hand, what if the person who comes looking for hospitality and perhaps for an opportunity to preach is one of these apostates? What if the person who knocks on the door and says, “I’m a Christian, may I stay here and share the Bible with you,” is one of these who denies one of the fundamental doctrines of the gospel? Then what?

John says, you do not receive him, and you do not greet him. You do not welcome him in as a fellow brother, because he isn’t one. You do not give his soul-destroying doctrine a warm bed and a nice hot meal. In fact, you do not even treat it in a regular fashion. You do not even greet it. The word for ‘greet’ is the Greek word for a very ordinary greeting, equivalent to hello, or keep well, good day, have a nice day, go well, goodbye. John says, when an apostate knocks on the door of your church, or of your house, you do not receive the apostate, or in any way acknowledge the person, in what they are doing.

Why John? Why the seemingly harsh treatment?

2 John 1:11

for he who greets him shares in his evil deeds.

This is the exact opposite of 3 John. When you receive and help true brothers, you are fellow workers of the truth. But when you receive and help gospel-deniers, you share in his evil. The word for share is the word koinonia – fellowships. When you host the apostate, when you give the pulpit to an apostate, when you give the impression to the apostate that he is doing good work, then you become part of his evil deeds.

To in any way recognise and help, or be courteous to the person involved in doing soul-destroying work, is not loving to them, or to the people they will confuse and twist. You see, John is saying the gospel is the boundary of Christianity, therefore we do not extend Christian recognition to a person who denies the gospel. We do not call him brother or call her sister. We do not say, ‘Thanks for your work for the kingdom of God’. We do not say, “Come on in, and let’s trade views, because yours is as valid as mine.” If we do that, we take a big eraser, and begin to rub out the gospel as the boundary of Christianity. We say, the gospel is important, but not all-important. This person is also a Christian in his own way, so we endorse a false gospel. We give a helping hand to those who would lead others to hell.

A superficial reading makes us say, it’s not loving to treat people this way. A right reading leads us to say, John is so passionate about protecting Christian love, he is willing to be extremely firm. He is willing to have the wolf at the door start whining and saying, “How can you do this to me? And you call yourself a Christian? Jesus said He wanted us to all be one! What kind of love is this?” He’s willing to do that, because the true basis of Christian fellowship is the gospel. People who deny the gospel are not to be recognised as Christians.

John actually lived this out. The heretic who taught that Jesus had not come in the flesh was Cerinthus who taught that the Christ came upon the man Jesus and then left him. According to the early church leader Irenaeus, one of John’s disciples, Polycarp, told the story that John the Apostle, was once in a public bath house. When he found out Cerinthus was inside, he ran out yelling “Let us flee, lest the building fall down; for Cerinthus, the enemy of the truth, is inside!

What this means is when the Jehovah’s Witness comes knocking at your door, you do not invite them in for tea and a discussion. You meet them at the door or the gate or the intercom. You do not say, “No, thank you” because there is nothing they are doing worth thanking. You do not say “Have a nice day” because while they are handing out tickets to hell, we don’t want them to have a nice day. We’d prefer they have a miserable or calamitous day and stop destroying people. We see them and say, “You are telling lies about Jesus. You have been deceived and now you are part of the deception.” And then you close the door, put down the intercom or walk away.

This doesn’t mean that if you work with a cult member, or have a family member who is part of a cult like that, or an immediate neighbour who is one, that you cannot extend courtesy and love to them as neighbours. You can, and must. It is when they are claiming to be Christians, and spreading lies about Christ, spreading their false gospel, and expecting that you recognise them as Christians that God calls for such swift and firm treatment. It is when they are claiming to have the gospel on their lips that you take a big, thick, permanent black marker, and draw those gospel boundaries clearer than ever. Love is limited by truth. The truth’s basic and fundamental boundary is the gospel. When someone denies the gospel we do not extend Christian fellowship to them.

Right into our era, there are continued calls for Christians to unite. And you know what? I agree. Christians must unite. But who is a Christian? A Christian is one who believes the gospel. If we fudge on the gospel we do not have Christian fellowship.

That kind of vagueness, that kind of fudging of the boundary of Christianity is what John is writing against. He even encourages us by way of future reward to love in the truth.

2 John 1:8

Look to yourselves, that we do not lose those things we worked for, but that we may receive a full reward.

Here is a possible negative consequence if we do not practise the truth. John says, there is a possibility of loss. He probably doesn’t mean you lose existing rewards. He means you lose what you could have gained. You lose out on a full reward. Why? Because God’s people partnering with apostates is scandalous. Demeaning the gospel by making it inconsequential is scandalous. Erasing the boundary line of the gospel to have an outward appearance of love and tolerance is scandalous. Compromising the gospel to gain political power and the appearance of unity is scandalous.

The church I pastor is a confessional Baptist church. That means we make use of creeds and confessions to draw boundaries. We say, if you believe this gospel, you are a Christian. If you do not, you aren’t. It is deliberately exclusive, because in that exclusivity, we bring clarity. We do that because we believe it is loving to do so. Clarity is loving. It is loving to make the gospel very clear, and show people who is in, and who is out. It is loving because we want to love one another. But we need to know who is a brother and sister to be loved as Christ loved us, and who is a neighbour to be evangelised.

That’s why we love in the truth. Our love is limited by and constrained by the truth. Fundamentally, it is the truth of the gospel. The gospel is the boundary of Christianity. To respect and protect the gospel is to love in the truth. That’s the message of 2 John.