John 13: 24 - 25 (NIV): 34 "A new command I give you: Love one another. As I have loved you, so you must love one another. 35 By this all men will know that you are my disciples, if you love one another."
It was just hours before Jesus was betrayed and arrested. Hours before he would be whipped and beaten and nailed to a cross. Hours before he became sin for us, paid the price for it, dying in agony. Jesus had just washed his disciples' feet -- even Judas' feet. In a little while Judas would betray him and the disciples would run scared into the night. Peter would deny three times that he knew him.
Then Jesus pronounced a new command. You could call this the Eleventh Commandment. Jesus was elevating us loving each other to the status of being equal to the Ten Commandments. It's not that the command for us to love each other was new. God had already told the Israelites to love each other as they loved themselves (Leviticus 19:18). But Jesus was putting love at the top of what we should do as Christians to show the world who we are. And they were about to understand what loving each other really meant. Love involves sacrifice. Showing true love for someone costs you. Moments later, Jesus would say, "greater love has no one than this, that he lay down his life for his friends." (John 15:13).
Now we understand what it means to love each other. When Jesus washed his disciples feet, he showed that love is humble, that love is a servant, and that love forgives. He knew full well that they were all about to let him down.
The first word in the Catholic Holy Thursday liturgy is "Mandatum", which is Latin for mandate or command. This is where the term "Maundy" comes from. Many Christians recognize Maundy Thursday as the day Jesus washed his disciples' feet and issued a new command, that we love one another as he loved us. Because the disciples showed true, sacrificial love for one another, Christianity soon conquered Rome and is on its way to overtaking the whole world. But it will only do so if we continue to follow Jesus' command and love one another as he has loved us.