To love wasn’t new. Certainly, throughout the Old Testament we ar, taught to love God. Deuteronomy 6:5 says, “You must love the Lord your God with all your heart and with all your soul and with all your might.” If that sounds familiar, it should – because in the Gospel of Mark, when Jesus was asked “what is the most important commandment?” He replied,
“The most important commandment is: ‘Listen, Israel, the Lord our God, the Lord is one. 30 Love[a] the Lord your God with all your heart, with all your soul, with all your mind, and with all your strength.’[b] 31 The second is: ‘Love your neighbor as yourself.’[c] There is no other commandment greater than these.”
Ok, so to “Love one another” must be the new part – right? No, even this was taught to the people of God long before Christ said it to His disciples. God told Moses to use the same words to teach His people about love in Leviticus 19:18:
You must not take vengeance or bear a grudge against any of your people, but you must love your neighbor as yourself. I am the Lord.
So, if “Loving one another” isn’t new why did Jesus say this was a “new commandment”? Because here in John 13:34, Jesus clarifies the command with these words:
Just as I have loved you, you are also to love one another.
The “new commandment” was and is, “Just as I have loved you, you are also to love one another” This means I have to know how He loved. What did He do? What didn’t He do? Why and how and all of the other explorative questions we can think of must be examined. It is only in knowing these answers that we will be able to fulfill this commandment, a command that Jesus references in His response to what the greatest commandment is.
One final note, in case, for even a moment of time, we think this applies to only the people that are good and nice to us – in case we want to justify not loving those who have mistreated us, spoke evil of us, or worse – we must remember that when we were the enemies of God, Christ came and died for us. It is to that end that we must live and love like Jesus.