By this all people will know that you are my disciples, if you have love for one another.
Jesus gave His disciples a new standard for love by visibly humbling Himself to wash their feet. He let them know that serving someone is the clearest definition of love if self-sacrifice drives that service. And by doing so Himself, Jesus calls us to serve one another in His love. Real love serves.
Real love is humble. It will not care to be applauded. Real love washes feet. It will do the menial task gladly for the other person. Real love is tangible. It gets itself dirty and cares to work for the benefit of another. It is seen in serving actions and not in flowery statements of intention. It makes no demands, but serves without distinction. Jesus even washed the feet of Judas without pausing. Such love is not glamorous, for slaves and foot-washers aren't celebraties. Real love is not consumeristic, driving for what it wants. Real love simply, and humbly, serves.
And Jesus says that sacrificial, humble love speaks to the world about Him. Jesus is known in our modern equivalent of foot-washing love. The church is so different from the world that our relationships grab the attention of those God is drawing to Himself. They will see real love. And that is how we can be credible with the gospel message.