We are now going to begin considering the actual terms of the New Covenant as John recorded them in his gospel.
We
 have seen that in Jn 13:30 Judas left to betray Jesus to the 
authorities. The following few words are Jesus' introductory remarks and
 the terms of the New Covenant begin at Jn 13:34 with the following 
words:
A new command I give you: Love one another. As I have 
loved you, so you must love one another. By this everyone will know that
 you are my disciples, if you love one another.
Notice how 
the very first words of the Covenant, the first obligation laid upon us,
 is to love our brothers and sisters in the faith. I find it fascinating
 that John and Peter, who were both present, emphasised this love for 
one another in their epistles and used the presence of such love as 
evidence of whether or not we are true disciples of Jesus.
Peter's Perspective
Peter, for example says:
Now
 that you have purified yourselves by obeying the truth so that you have
 sincere love for your brothers, love one another deeply, from the 
heart. (1 Pet 1:22)
This is not a soppy, mushy kind of love because as he goes on to say later in chapter 4 verse 8:
Above all, love each other deeply, because love covers over a multitude of sins.
Loving
 our brothers like this is worked out practically in forgiveness. 
Remember the earlier words of Jesus when Peter asked him about this as 
recorded in Matthew 18:21-22:
Then Peter came to Jesus and 
asked, “Lord, how many times shall I forgive my brother when he sins 
against me? Up to seven times?” Jesus answered, “I tell you, not seven 
times, but seventy-seven times."
Loving one another means 
complete forgiveness. But it also means protecting the sinner. When we 
cover the sins of another, we do not broadcast them to the world but 
rather seek to protect them, to nurture them and to bring them back to 
wholeness. The aim should always be to restore the sinner.
John's Judgement
John's
 epistles frequently bring out the concept that our love for one another
 is evidence of our love for God or, conversely, that we cannot claim to
 love God if we do not love our brother.
If anyone says, “I 
love God,” yet hates his brother, he is a liar. For anyone who does not 
love his brother, whom he has seen, cannot love God, whom he has not 
seen. (1 Jn 4:20)
Like Peter, John also gives a practical 
example of the outworking of this love but rather than focusing on 
forgiveness of the sinner he looks to the need of the brother:
If anyone has material possessions and sees his brother in need but has no pity on him, how can the love of God be in him? (1 Jn 3:17)
Love
 in this case is worked out by making sure our fellow believers are not 
going hungry or are in any other kind of need. Paul made such a radical 
statement about this in 2 Corinthians 8:13 that I have never heard it 
preached on:
Our desire is not that others might be relieved while you are hard pressed, but that there might be equality.
Equality? I have seen a lot of love and care within the church but 
never a drive towards equality amongst its members. Why is that?
God's Glory
 
I
 want to make one final observation about this command of Jesus. Notice 
what He doesn't say. He doesn't say, "By this everyone will know that 
you are my disciples, if you love others," but "if you love one 
another."
We get caught in the trap of thinking that the world 
will recognise we are Christians if we show love to those outside our 
own community of believers. But that isn't the case. What evidences that
 we are Christians, and so brings glory to God, is the care we show 
towards His own people. Again Paul has something to say about this:
Let
 us not become weary in doing good, for at the proper time we will reap a
 harvest if we do not give up. Therefore, as we have opportunity, let us
 do good to all people, especially to those who belong to the family of believers. (Gal 6:9-10 emph. added)
God is glorified when we place the emphasis on showing love to our brothers and sisters in practical ways.