In John 13:34-35, Jesus tells his disciples, “³⁴ A new commandment I give to you, that you love one another: just as I have loved you, you also are to love one another. ³⁵ By this all people will know that you are my disciples, if you have love for one another.”

So how will people know that Christians really are who they claim to be and that their message is legitimate? By the love we have for one another.

As Christians, our love for one another is a huge part of our witness to the world. It might even be the most important thing that helps people see how true the gospel is. It’s the key piece of evidence.

Because, when you think about it, you can’t see the gospel. There’s nobody walking around today who was alive 2,000 years ago and could be an eyewitness to Jesus rising from the dead.

So how can we know the gospel is true? We can’t see it. We can’t do a series of empirical tests and verify that the gospel’s true. So where’s the evidence that confirms the truth of the gospel?

Well, the evidence is in our lives. We know the gospel is true because of the results it produces within us—results that are nothing short of miraculous. The gospel changes us and makes us into new people and teaches us, among other things, to live together in love. So when we as believers exhibit that love, people know that the gospel is true.

You might compare it to gravity. Gravity itself is invisible. So how do you know that gravity exists? Well, I’m sure a scientist could make a case that gravity exists by telling us all about complex formulas and statistics. But I’m pretty sure just about all of that go would go right over most people’s heads. Most people probably wouldn’t be able to understand what he’s talking about and therefore wouldn’t find his arguments very persuasive.

The best way to prove gravity exists is simply to drop an object and watch it fall. That’s all it takes. We know gravity exists because of the way it affects objects when drop them. We know it’s real by the effect it has.

And it’s the same way with the gospel. How can people know the gospel’s true? How can people know that Jesus really came from God and died for our sins and rose again from the dead? It’s by the way that gospel message changes us as followers of Jesus.

So if you’re a Christian, is your life a convincing testimony?