Jesus knows he is about to be betrayed, knows of his approaching death, and we readers or hearers know as well, putting us at a bit of an advantage over the disciples at dinner. Jesus takes the opportunity to prepare his disciples for the future, and thereby the evangelist takes the opportunity to remind us of several important points for the Christian community as to the nature of Jesus, the promise of the Holy Spirit, or Advocate, and the commandment -- should we miss all of the rest of the message, the one thing Jesus would have us do: love one another. This commandment is given after the one major action of John's story of the Last Supper, when Jesus washes the feet of his disciples.
John 13. Now before the festival of the Passover, Jesus knew that his hour had come to depart from this world and go to the Father. Having loved his own who were in the world, he loved them to the end.
2 The devil had already put it into the heart of Judas son of Simon Iscariot to betray him. And during supper
3 Jesus, knowing that the Father had given all things into his hands, and that he had come from God and was going to God,
4 got up from the table, took off his outer robe, and tied a towel around himself.
5 Then he poured water into a basin and began to wash the disciples’ feet and to wipe them with the towel that was tied around him.
6 He came to Simon Peter, who said to him, ‘Lord, are you going to wash my feet?’
7 Jesus answered, ‘You do not know now what I am doing, but later you will understand.’
8 Peter said to him, ‘You will never wash my feet.’ Jesus answered, ‘Unless I wash you, you have no share with me.’
9 Simon Peter said to him, ‘Lord, not my feet only but also my hands and my head!’
10 Jesus said to him, ‘One who has bathed does not need to wash, except for the feet, but is entirely clean. And you are clean, though not all of you.’
11 For he knew who was to betray him; for this reason he said, ‘Not all of you are clean.’
12 After he had washed their feet, had put on his robe, and had returned to the table, he said to them, ‘Do you know what I have done to you?
13 You call me Teacher and Lord—and you are right, for that is what I am.
14 So if I, your Lord and Teacher, have washed your feet, you also ought to wash one another’s feet.
15 For I have set you an example, that you also should do as I have done to you.
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34 I give you a new commandment, that you love one another. Just as I have loved you, you also should love one another.
35 By this everyone will know that you are my disciples, if you have love for one another.’
The context is not accidental. Love brackets the story of the washing of the feet. The love Jesus is commanding is not just a warm fuzzy feeling for one's fellow human being. It means caring for one another in physical and intimate ways. It means caring to the point of putting oneself in what the "world", the world of status and power and wealth and privilege, would consider a subservient or demeaning position. Christianity, after all, is about Incarnation, physical presence of God in human form, as much as about Resurrection, a transcendence of the limit of death that is usual in the physical world.
Where is the good news in that? It is in the affirmation that our physical (and emotional and psychological, and intellectual) needs should be a concern to one another, and, despite centuries of Christian distrust of the physical, the body, these needs should not be denied or vilified. Danger is not in our physical being, but in that which keeps us from loving one another.