Building Up: True Love

How are people in the world supposed to be able to tell who are the true followers of Jesus? We might have a number of identifying marks that come to mind (holiness, holding to God’s truth, a concern for the spiritually lost, etc.). All of these things should be true of genuine disciples of Jesus Christ. But Jesus said, “by this all people will know that you are my disciples, if you have love for one another” (John 13:35). Why would He say that? And why would Paul insert a discourse on love right in the middle of his teaching on spiritual gifts?