The Hidden Poison and the Purifying Cross

There’s a kind of poison that doesn’t smell, doesn’t taste, and doesn’t show itself until it’s far too late. A single drop of potassium cyanide, undetectable to the senses, can bring death within minutes. The danger isn’t in how much you see — it’s in how much you ignore.
Sin works the same way.

In 1 Corinthians 5, Paul warns the church about a quiet, tolerated sin that had begun to fester within the body of Christ. Not dramatic. Not headline-making. Just persistent, unrepentant compromise. A little leaven, he says, leavens the whole lump. And his words are not measured. They’re surgical. Urgent.

 “Cleanse out the old leaven,” he writes, “that you may be a new lump, as you really are unleavened.”

This is not moralism. It’s not behavior management. It’s not “do better.” It’s the gospel in motion — a call to live out what Christ has already made true. “Christ, our Passover Lamb, has been sacrificed.” That’s the foundation. The cross is not casual about sin. It’s the place where sin was crushed, where holiness and love collided, and where sinners like us found life.

And so the church is called to reflect that holiness. Not with cold legalism. Not with arrogant judgment. But with tears, love, and courage. We don’t pursue purity to earn God’s love; we pursue purity because we’ve already been given it.

That means we deal with sin — in ourselves, and in our community. We don’t ignore it. We don’t excuse it. We don’t let it quietly shape our churches while we turn our heads and talk about the sins “out there.” Paul says, “God judges those outside.” But we are called to be stewards of holiness inside.

This is hard. It will take humility, wisdom, and Spirit-filled courage. But it is good. And it is freeing. Because Christ didn’t die for a half-hearted bride. He died to make her radiant. Pure. Holy.
Let us, then, cleanse the leaven — not to become something we’re not, but to live as the unleavened people we already are.

Because the cross didn’t just forgive us.
It purified us.
And it still does.
Have you confessed what needs confessing?
Is there leaven that needs to be purged?
Don’t wait. The poison spreads silently.
But the cross still heals completely.