How would you know if your faith was real?
Not whether you’d prayed the right prayer once, or whether your name is on a church membership list somewhere. I mean the deeper, more unsettling question: if you stripped away the language and the habits and the Sunday routine, is there anything underneath that would prove the thing is actually alive?
That’s the question the apostle John keeps circling in his first letter. And in the middle of it, in chapter 3, he hands us a test – though not the kind of test we might expect. It isn’t a doctrine quiz. It’s a mirror. And I’ll be honest with you before we start: it’s a mirror that rubs most of us up the wrong way.
A quick word on the letter
If you’ve never read 1 John, here’s the lay of the land. John was one of Jesus’ closest friends, and he wrote this letter near the end of the first century to a group of Christians who were being unsettled by a counterfeit gospel doing the rounds. His main aim was assurance – to help ordinary believers know, deep in their bones, that they really did belong to God.
One writer describes the letter as a slow climb up a spiral staircase: the higher you go, the more deeply the same simple truths get laid out in front of you. Chapters 1 and 2 mostly work one contrast – light and darkness. Then, at chapter 3, John sets up a new one: love and hate.
And it all serves that single pastoral question – how do you know your faith is real? John isn’t handing you a checklist to run over other people to work out who’s in and who’s out. That misses him completely. He’s speaking to you, personally, about what your own faith will look like if it’s the genuine article.
Here’s the passage. I’m using the NIV.
11 For this is the message you heard from the beginning: We should love one another.
12 Do not be like Cain, who belonged to the evil one and murdered his brother. And why did he murder him? Because his own actions were evil and his brother’s were righteous.
13 Do not be surprised, my brothers and sisters, if the world hates you. 14 We know that we have passed from death to life, because we love each other. Anyone who does not love remains in death. 15 Anyone who hates a brother or sister is a murderer, and you know that no murderer has eternal life residing in him.
16 This is how we know what love is: Jesus Christ laid down his life for us. And we ought to lay down our lives for our brothers and sisters. 17 If anyone has material possessions and sees a brother or sister in need but has no pity on them, how can the love of God be in that person?
18 Dear children, let us not love with words or speech but with actions and in truth.
Who do you belong to?
Verse 11 doesn’t start a fresh thought – it continues one. The question running underneath the whole chapter is: who do you belong to? Read the verse just before our passage and you’ll see John lay it out plainly:
10 This is how we know who the children of God are and who the children of the devil are: Anyone who does not do what is right is not God’s child, nor is anyone who does not love their brother and sister.
Two families. Children of God, and children of the devil. And John is going to show us the marks of each. That’s the ground our passage stands on – so keep it in view.
Where love and hate come from
Watch how John defines hatred. He doesn’t reach for the culture around him. He doesn’t ask what seems loving to the people of his day. He goes all the way back to the first book of the Bible – to one of the oldest stories humanity has – and roots the whole thing there. (This is a very John thing to do, by the way. He’s forever linking everything back to the beginning, to show that what looks new was God’s plan all along.)
That instinct takes some getting used to, because we live in a culture that works the opposite way round.
Our age tends to see itself as the summit of progress – the enlightened end of a long climb out of ignorance, getting wiser and kinder with every passing year. And so love and hate get defined not by anything ancient or fixed, but by how tolerant or intolerant you are of the ideas currently in fashion.
Right now those ideas cluster heavily around sexuality and gender. In an age where, arguably, those categories have never been less defined, we’ve somehow tied our whole understanding of love and hate to how well you can keep pace with the shifting vocabulary. Love means ignoring differences. Love means declaring everyone equally special. And question the popular script, and you’re not merely mistaken – you’re guilty of hate.
John simply doesn’t work like that. He says love and hate were defined right at the beginning, almost as old as humanity itself. And notice where he plants his example – in the family. His picture of the kind of hatred that marks someone out as a child of the devil is drawn from how a man treated his own brother.
That matters for us, because John has already stretched the word “family” to cover the church. In Christ, the people you sit near on a Sunday aren’t your acquaintances. They’re not even just your friends. They’re your brothers and sisters – flesh and blood. So the question of how we love one another isn’t sentimental. It’s a family matter.
The story John reaches for
Before John tells us what love looks like, he shows us what it doesn’t, and he does it with Cain and Abel.
If the story’s unfamiliar, it’s from Genesis 4. Cain and Abel are two of Adam and Eve’s sons. Abel keeps livestock; Cain works the soil. Both bring an offering to God, and God responds to them differently.
Abel brings the firstborn of his flock, the fat portions – the very best of what he has. His heart is worship: God comes first, and it costs him something to give. Cain’s offering is described in a way that quietly falls short. It’s an afterthought – whatever came to hand.
God calls Cain on it. And instead of owning the failure, turning from it, and throwing himself on God’s mercy, Cain murders his brother.
That’s the story John picks to define hatred. And he interprets it for us. Genesis 4 doesn’t spell out Cain’s motive in so many words, but John does:
Do not be like Cain, who belonged to the evil one and murdered his brother. And why did he murder him? Because his own actions were evil and his brother’s were righteous.
Here’s the thing I don’t want you to miss, because it changes how this lands on us. The murder is the outcome. But the verse traces it back to something upstream – an attitude. And the attitude is what John is actually pressing on. The hand only did what the heart had already decided.
Which is exactly where Jesus takes it in the Sermon on the Mount:
But I tell you that anyone who is angry with a brother or sister will be subject to judgment. (Matthew 5:22)
So let me put an uncomfortable question to you. Is there someone in your church family you find it hard to like?
I’d wager there is. In any group of real human beings there’s usually one person who just gets under your skin – the tone of voice, the way they go on, whatever it is. And hear what I’m not saying: this passage is not a blanket condemnation of finding someone hard to like. It’s not a sin to click with some people more than others. But it does ask a searching question about what you then do with that dislike.
If you’re at all worried you might be looking more like a child of the devil than a child of God, three honest questions:
- Is there someone I actively avoid – someone I’ll steer around or find a reason to be somewhere else when they walk in?
- Is there someone I talk about behind their back more than anyone else?
- Is there someone I secretly wish would just go and worship somewhere else?
Murder is wrong. But so is the hatred that sits behind it. The feeling of dislike isn’t the sin – it’s the fork in the road. What you choose to do with it decides which way you’re walking: towards hatred, or away from it.
Don’t be surprised when the world hates you
Before John turns to love, he slips in a word of steadying comfort for anyone on the receiving end of hostility. Verse 13: do not be surprised if the world hates you.
Those of us in the comfortable West don’t often face persecution in the sharp way many believers around the world do. But John seems to assume that if you’re genuinely walking as a child of God, people will eventually notice the very thing Cain noticed in Abel – and some of them won’t like it. His reassurance isn’t “you’ll be fine.” It’s “don’t be shocked when it comes.”
Let me flip that round, though, because it cuts the other way too. John clearly expects hostility to be normal for a Christian. So when did you last experience anything even close to it for your faith? Right now, somewhere in the world, people are being asked whether Jesus is their Lord, and — knowing exactly what the answer will cost them – they’re going to their deaths saying yes rather than no. That puts a certain perspective on how we can flinch at the mild awkwardness of telling a colleague that Jesus loves them.
So here’s a genuinely searching question: do the people around you ever find you a bit strange? If the world never finds you the least bit odd, it’s worth asking why. Being universally liked is more likely to be a warning light than a gold star.
Real love is dying to yourself
All of which sets up the question John has been building towards. If hatred of our brothers and sisters marks us out as children of the devil, and love for one another is one of the surest signs we belong to God – then what does that love actually look like?
John answers it beautifully in verse 16:
This is how we know what love is: Jesus Christ laid down his life for us. And we ought to lay down our lives for our brothers and sisters.
The love we’re called to is self-sacrificial. It gives itself away at cost. Paul says the same thing in Romans:
But God demonstrates his own love for us in this: While we were still sinners, Christ died for us. (Romans 5:8)
Notice the timing. Christ didn’t wait for us to sort ourselves out first. He didn’t say, I’ll love you once you’ve cleaned up your act. At the very peak of our rebellion, He laid down His life. That’s staggering – and it’s the exact opposite of the love our culture keeps selling us.
Because love has been cheapened until it barely means anything at all. I was in the supermarket recently and saw someone wearing a T-shirt that read, across the back: Dear person behind me, I love you, you’re doing great. On the surface, lovely. But poke it and there’s nothing underneath. It’s cheap love – a warm feeling aimed at no one in particular, costing nothing.
Tim Keller, writing about marriage, puts his finger on why that rings hollow:
To be loved but not known is comforting but superficial.
That supermarket T-shirt is exactly that – comforting, and completely superficial. You see the same thing every time there’s a tragedy and a politician reaches for “my thoughts and prayers are with the victims and their families.” It sounds kind. But I doubt their thoughts are entirely with those families rather than the afternoon’s meetings – and I’m sceptical some of them have done a day’s praying in their lives. Warm words, and nothing behind them.
That’s not the love we’re called to. Keller finishes the thought like this:
To be known and not loved is our greatest fear. But to be fully known and truly loved is, well, a lot like being loved by God. It is what we need more than anything. It liberates us from pretense, humbles us out of our self-righteousness, and fortifies us for any difficulty life can throw at us.
That is precisely the love Christ shows you. He knows you completely – everything you’ve thought and done and said – and He laid down His life for you anyway, and still holds out an eternal inheritance. Fully known, and truly loved.
And that is the love we’re now meant to hand on.
So think back to the person you find hard to like. Knowing all you know about them – the grating voice, the constant moaning, whatever it is – how do you love them? You love them at real cost to yourself. You stop putting yourself first when they’re in the room. You stop avoiding them. You give them your time. You quietly die to your own preferences and start living as though they mattered.
I know plenty of relationships between good Christian people that have simply broken down. And in almost every case, both parties have perfectly valid reasons for not getting on. But when I look honestly at those situations, the way out is nearly always the same: someone has to stop protecting their own comfort and start living as if the other person mattered more than their being in the right.
And if you’re reading that thinking I just don’t have it in me – here’s some very practical wisdom from C.S. Lewis, in Mere Christianity:
Do not waste time bothering whether you ‘love’ your neighbour; act as if you did… When you are behaving as if you loved someone, you will presently come to love him.
John lands in the same place – love proved by action, not sentiment. Verse 17:
If anyone has material possessions and sees a brother or sister in need but has no pity on them, how can the love of God be in that person?
Now, a word we all need to keep hearing: none of this earns your salvation. It never has and never could. Your actions don’t buy God’s favour. But how you act in response to being saved is exactly the evidence John points to for assurance that you really are a child of God. The love isn’t the root; it’s the fruit.
And if you’re sitting there uneasy because you recognise more of Cain in yourself than you’d like – that’s not a dead end. That’s an open door. The honest thing to do is to stop, humble yourself, and receive from Christ the very thing only He can give.
So what do we do with this?
Studying the Bible is only worth anything if the truth actually reaches our own lives. So let me press this down into three practical points.
1. Let Scripture, not the culture, define love and hate. John grounds both in the Bible’s oldest story, not in the mood of the moment. So don’t let your experiences, or the culture, or the loudest voices online reshape what love is. Stand on what God has actually said.
2. If you’re at odds with someone, be reconciled. John – and Jesus before him – link contempt and anger among family to murder itself. So: is there anyone in your church you’re avoiding? A relationship that’s soured? Any bitterness or resentment you’re quietly nursing? If this has stirred something in you, don’t file it away for later. Apologise. Forgive. Make peace.
3. Expect love to cost you. The love we’re called to – the love Jesus showed us – costs time, money, comfort and effort. When did you last genuinely put another believer’s needs ahead of your own? Is there someone God is pressing on your heart right now to show the same love you were shown at the cross?
John’s letter was never meant to be a rulebook. It’s an attempt to ground the Christian life in the truth of the gospel and set it hard against the lies of the world. It’s written to assure ordinary Christians that they really are saved – and to stir them to drop whatever’s holding them back.
But above all of that, it’s a portrait of Jesus. So the most fitting response to any of this isn’t to grit our teeth and try harder. It’s to fix our eyes on Him – to adore Him for the love He’s shown us, and to ask His Spirit to make us into people who love the way He loves, and live the way He lives.