Of everything Jesus could have chosen as the defining mark of His followers, He chose love. Not correct doctrine, though that matters. Not impressive gatherings, though there is nothing wrong with those either. Love. “A new commandment I give you: Love one another. As I have loved you, so you also must love one another. By this everyone will know that you are My disciples, if you love one another” (John 13:34–35).

Read that closely, and one word should stop you: new. The command to love was not new. It runs right through the Old Testament. What was new was the measure. As I have loved you. Not as much as is convenient. Not as much as feels natural. As Jesus loved. That is an entirely different standard, and it is meant to be visible enough that people outside the church notice it.

Now, that raises an honest question. If love really is meant to be the identifying mark of a healthy church, why is it so often the thing churches are known for least? It is not usually because anyone decided to stop loving one another. It is because busyness, distance, and comfort quietly crowd it out. It is far easier to sit in a room with the same people every week and never actually know them than most of us would like to admit.

So what does this kind of love actually look like in practice, rather than just in a sermon? It looks ordinary, most of the time. It looks like noticing who was not there this week, and following up. It looks like sitting with someone in a hard season without rushing to fix it or move the conversation along. It looks like being patient with someone who is difficult to be patient with, and staying anyway. It looks like sharing what you have, your time, your table, your home, without keeping score.

This kind of love is costly precisely because it is not a feeling that simply arrives on its own. It is a decision, renewed constantly, to keep choosing people even when they are inconvenient, even when they have hurt you, even when loving them well will cost you something real.

And here is what makes it worth it. Jesus did not simply command this love. He said something remarkable would happen because of it: the world would know. Not because of a clever argument, not because of an impressive building, but because of the way believers actually treated one another. Love that is only felt in private does not accomplish what Jesus described. It has to be visible, lived out in ordinary weeks, noticed by people who are simply watching from the outside.

That is a high calling, and an honest one. But it is also, in the end, the simplest test of whether a church is healthy. Not how well it teaches, though that matters. Not how well it gathers, though that matters too. But whether the people inside it actually, visibly, costingly love one another.