The Diamond of Assurance: Repentance & Belief


How do I know I am really a Christian? Why do I doubt so much? Should Christians be sinning as much as I do? What happens if God doesn’t love me anymore?

These doubts and more are questions I’ve heard Christians ask when they lack assurance of their salvation. I have asked many of these questions myself. The lack of answers bring heartache and spiritual depression. We start comparing ourselves with others more ‘spiritual’ and we see how much of a failure we are.

What do we do when we are confronted with these problems?

Well, there’s no fool proof method or test that can help every Christian in the same way. We can’t do a blood test to assess whether we’re ‘in Christ’. Only God can see our hearts. And the Christian life is a messy life, full of failures and heartbreaks and struggles. There will be ups and downs. The conflict with sin is not over until Christ returns.

But here’s something that I think can help. I’ve called it the ‘Diamond of Assurance’, because – well the picture looks like a diamond. And because a diamond evokes at least three qualities that we want to see in the Christian life.

1: A diamond is unbreakable. It is the hardest natural mineral on the planet. And we want a faith like it don’t we? A faith that is unbreakable – unyielding in its desire to follow Jesus. In our struggles, no matter how hard life beats against us, no matter how much we struggle with sin and tragedy, we want our faith to be diamond strong. We want unbreakable faith.

2: A diamond is beautiful. There is something intrinsically beautiful about a clear pure diamond. And we want our faith to look beautiful – not because we try hard to look good – but because our faith is directed towards our beautiful Saviour and should reflect him in our lives. We want a beautiful faith.

3: A diamond is precious. We know this because many of the most expensive or impressive diamonds are kept locked in vaults and are ridiculously expensive. But Peter says our faith is more precious than gold, because ultimately through the purifying process of hardship it will result in us glorifying Jesus when he returns.[1] Gold can only buy you riches on earth, faith in Jesus results in riches in heaven. We want a faith that is precious.

The Diamond of Assurance


So how do we get a faith that is unbreakable, beautiful and precious? Well at one very important level we don’t. As the diamond picture shows, such things cannot be achieved through merely outward effort. After all, our problem is a heart problem. That’s where the Holy Spirit comes in. You might have heard of the phrase, the diamond in the rough. Well here we have the Holy Spirit in the diamond. He is the one at work in us who can make our faith unbreakable, beautiful and precious. How? Ultimately by making us more like Jesus.


The four points of the diamond are the outward indicators that the Holy Spirit is doing his work in our lives, transforming us to become more like our Saviour. When someone says – ‘how do I know I’m a Christian?’ we can point to these four areas that reflect the Holy Spirit’s transforming power.

1: Repentance & Belief

2: Fruit

3: Endurance

4: Church Fellowship

If we can point to evidence that these four facets of the diamond are visible in our lives, then I believe this goes a long way to assuring a doubting brother or sister that they are ‘in Christ’. Over the next few weeks, we’ll be taking a look at each of these four points in greater detail to encourage us in our faith.


At the top of the diamond is perhaps the most basic and yet the most important. To have assurance that we are a Christian we need to have repented and believed in Jesus. Jesus himself said in his first command of Mark’s Gospel: ‘Repent and believe in the gospel’.[2] We know that Mark’s Gospel is the good news about ‘Jesus the Messiah, the Son of God’ because that’s how it starts.[3]

So, repenting and believing in Jesus is essential to Christian assurance. We cannot claim to be a Christian if we don’t believe in Jesus and have turned to him as our Lord and Saviour.

Let me break these down by looking at belief first.


To believe is to trust in the saving work of Jesus. To trust that Jesus is our Lord and Saviour, and that his blood bought sacrifice on the cross is enough to save us. There’s no sin too great that hasn’t been wiped out by his blood.

Trusting in the risen Jesus is the key and he gives us this strength through the Holy Spirit working in us, showing us that Jesus is our wonderful Saviour. Trusting in Jesus means we can rest in the reality that God the Father has adopted us into his family. We are his and nothing can separate us from the love of God that is in Jesus![4] Our rebellion will never undo the finished work of the cross. So, keep trusting in Jesus and remember he is enough.


Christianity isn’t based on good works, but grace. We don’t keep living the life we’ve always lived. We realise that God has given us the free gift of salvation which is totally undeserved! And at that point our lives change forever.

When we grasp God’s grace in our lives, we turn from worshipping self or created things and turn to Jesus. Through the power of the Holy Spirit we are given a new heart which enables us to turn from rebellion to repentance. And repentance is declaring that Jesus is Lord.

This is something we do when we first become a Christian and is something we never stop doing. Repentance is the outward reality of the Holy Spirit working in our hearts. The outward reality of us turning from sin and turning to Jesus. It is this daily posture, this daily attitude that is the sign that our hearts now pledge allegiance to King Jesus.

[1] 1 Peter 1:6-7

[2] Mark 1:15

[3] Mark 1:1

[4] Romans 8:38-39.

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