Written on Our Hearts

9 Oct

Jeremiah 31:31-34

There's a note on the freezer. It says, in big red letters, don't eat the ice cream. It's clear. It's direct. It's even written in capitals, which means it's basically shouting. By 10.00 pm, the ice cream is gone.

That's the problem with law written on stone.

We've just finished a series on the Ten Commandments, ten sentences that turned out to be far deeper than any of us expected. The whole time, we've been saying that the commandments are actually a freeing thing, not a restricting one. They're not a killjoy God putting barriers around his people. They're a loving Father drawing boundaries for their flourishing, the way any good parent does, not to hinder, but to protect and shape.

But here's the honest question sitting at the end of that series, right before we move into Galatians: if the commandments are good, why couldn't they change us? And if they couldn't change us, what were they actually for?

Jeremiah 31 is the answer.

A Husband, Not a Policeman

Before we get to Jeremiah's solution, we need to sit with something he says about the problem.

God speaks through Jeremiah about the covenant he made with Israel, the one they broke, and he describes himself not as a judge, not as a policeman, but as a husband.

“Though I was a husband to them, declares the Lord.”

That reframes everything. When we break God's commands, the natural instinct is to think of it as rule-breaking; we violated a regulation, we failed a standard, we need to face the consequences.

But Jeremiah is saying something more intimate and more painful than that. It's not rule-breaking. It's covenant-breaking. It's the kind of betrayal that happens between people who have promised themselves to each other.

The very first commandment, have no other gods before me, is the language of marriage vows. An exclusive covenant. When Israel worshipped the golden calf while Moses was still coming down the mountain, they weren't just breaking a regulation, they were committing adultery against the one who had brought them out of slavery and called them his own.

How we think about this matters more than we realise. If we see God as a policeman, sin is just rule-breaking and God is judge and jury. But if we see him as a husband, as a loving Father who draws close to his people, then sin is something that should grieve us precisely because it hurts someone who loves us.

The good news is that a husband can forgive in a way that a policeman never can.

The Location Problem

So what went wrong? Jeremiah is clear: the problem wasn't the content of the law. God didn't get the commandments wrong, and Moses's decision to smash the first set didn't give God an opportunity to produce a better list. The Ten Commandments were good. They still are.

The problem was the location.

The law was written on stone; outside of people, carried around and read, informative but ultimately unable to change what was happening inside. Like the note on the freezer. Clearly worded, accurately placed, completely ineffective at 10 pm.

Ezekiel puts it even more vividly: I will remove from you your heart of stone and give you a heart of flesh. A heart of stone can't be changed by more stone. What it needs is surgery. A replacement. Something that beats differently.

And so God promises something entirely different through Jeremiah.

Three Promises

Jeremiah 31:33–34 gives us three promises flowing from the new covenant:

The first:

I will put my law in their minds and write it on their hearts.

Law on the inside, not the outside. Obedience that comes from within, not from external pressure or compliance. The difference between I have to and I want to. How often do we describe church attendance, Bible reading, prayer — the habits of the Christian life — as things we have to do? The promise of the new covenant is that God is working to make them things we want to do. Not by removing the effort, but by changing the heart that brings the effort.

The second:

No longer will they teach their neighbour or say to one another, know the Lord, because they will all know me, from the least of them to the greatest.

This isn't saying we stop teaching each other, the whole church exists partly for that. It's saying that knowledge of God won't be the exclusive territory of the religious elite, the spiritually gifted, the people who seem to have it all together. Everyone who belongs to God will know him. Young and old, new and long-standing, confident and struggling.

The third, and the one that lands hardest:

For I will forgive their wickedness and will remember their sins no more.

Not an interest-free payment plan where the debt is slowly worked off. Not a conditional forgiveness that gets revoked if old patterns resurface. He remembers them no more. Not because he forgot, but because in Jesus, he remembered them fully, poured them all onto him, let the weight of every sin fall on the one who had never broken a single commandment, so that when he looks at us, the account reads paid in full.

The New Covenant in Jesus

Jesus himself picks up this language at the Last Supper. This cup is the new covenant in my blood, which is poured out for you. The covenant Jeremiah was pointing to is the one sealed in Jesus's death and resurrection. Everything Jeremiah promises, the law on the heart, knowledge of God for all, sins remembered no more, is what Jesus accomplished and what the Spirit now works out in everyone who trusts in him.

Tim Keller put it simply:

“The gospel says that you and I are simultaneously more sinful and flawed than we ever dared believe, yet more loved and accepted than we ever dared hope.”

Both halves matter. We are more broken than we want to admit, our series on the Ten Commandments should have made that clear. But we are also more loved than we imagined. Not despite the brokenness. Through it. Because God looked at it fully, in all its weight, and put it on Jesus, and then looked at us and said: remembered no more.

Growing Into It

With the law now written on our hearts through the Spirit, the right question to ask about our growth isn't how do I compare to other people? It's am I becoming more patient than I was two years ago? Am I kinder? Am I more honest? Is there fruit I can point to, even slowly, even quietly, that the Spirit has been working in me?

We're often hard on ourselves and gracious with others, which means if you can't see the growth, it might be worth asking someone who knows you. They'll probably have a longer list than you do.

The Spirit is at work. The law is being written on hearts, not just held in front of faces. And the God who made that promise through Jeremiah sealed it in the blood of his son.

I want to, not I have to.