By this shall all know that ye are disciples of mine, if ye have love amongst yourselves.
Jesus is about to be taken from His disciples, and He tells them what will mark them out once He is no longer with them. The sign He chooses is not their teaching or their gifts but their love for each other — and He says the world will read it.
A Sign Left Behind
The disciples would soon be left without Him. One writer ties the sign to that absence — they would be His disciples with Him gone, and one thing would show it:
But though they were not with Him, they were His disciples. One thing made this clear: a new commandment — and He was One who could give a new commandment. It was, "That you love one another." The commandment came from Him to them, a sign in them, telling unbelievers that they were His disciples. This was the sign to the world.
The Measure Is His Own Love
Christ sets the standard by His own love, not by their love for Him. One commentator notes how the Lord words it:
The Lord's love to them was pure, patient, untiring, persevering; it never flagged. Nothing on their part could turn it aside. Nothing less than this is the pattern of their mutual love. The Lord does not say, Love Me as I have loved you; it is, Love each other as I have loved you.
Not a Law, but a Nature
This is not another rule laid on human strength. It fits a nature they had already received:
He has one striking new commandment to leave with them. It is not a legal commandment, as those given by Moses, and nothing that would tend to puff up the flesh. He had loved them: let them show the same love toward one another. Indeed, His love was because of His very nature: they too had been given this blessed nature by new birth. The command therefore is really to allow that nature its proper expression.
The world had no such love until Christ appeared:
Love is of God, not of man, which accounts for the blank until He came Who, though God, showed love in man and to man... This is not zeal that goes out searching for sinners, precious as that is. It is the unselfish seeking of the good of believers as believers, in humility of mind and in Christ's love.
A Mark the World Can Read
Love like this looks out of place in the world, and that is what makes it visible:
A company marked by love would look so strange in a place ruled by lust and selfishness that even the world would realise these people must be the disciples of Christ. The world cannot appreciate the faith and hope of Christians. But divine love and what it does they can at least see and admire, even if they cannot imitate it.
The other marks of following Christ look like folly to onlookers:
A disciple giving up everything to follow Christ would be thought a fool... In chapter 13 the Lord gives a mark that the natural man can recognise. It might make him wonder, but it would be clear evidence of a power greater than the selfishness of nature.
A Witness Open to Everyone
Not every Christian can preach. One writer points to a testimony that leaves no one out:
Now love to fellow believers is evidence of divine life. It is evidence first to ourselves: "We know that we have passed out of death into life, because we love the brothers" (1 John 3:14). Second, it is evidence to the world: "by this all people will know that you are my disciples, if you have love for one another" (John 13:35)... Do you want to bear testimony for Christ, to preach the gospel? Good! it is a good desire. But not everyone is gifted for this. Yet there is a testimony everyone can display, even the humblest: he is greatest who shows it most, and the most splendid gift is nothing without it. It is love!
An Honest Look at the Result
One writer turns the verse into a test, and applies it to the state of Christians:
So what proves that we are the disciples of Christ is not holding certain truths, and not having light, but loving one another. Let us not shrink from facing this divine fact. As we face it, let us ask ourselves whether this testimony has failed completely. The broken state of the Church, the divisions across the Christian world, and rival parties and jealousies all proclaim our disgrace.
Summary
- Absence. Christ was going away, and left one visible sign that they still belonged to Him.
- Pattern. The measure is not their love for Him but His for them — pure, patient, untiring, never turned aside.
- Source. It is not a law added to human effort; it is the new nature from new birth showing itself.
- Reach. The world cannot appreciate faith and hope. But it can see and admire love in a selfish world, even if it cannot copy it.
- Verdict. Holding truth is not the sign. Love among believers is — and divisions among Christians are the plainest confession of failure.