At supper with his friends, Jesus was troubled in spirit, and declared, "Very truly, I tell you, one of you will betray me." The disciples looked at one another, uncertain of whom he was speaking. One of his disciples-- the one whom Jesus loved-- was reclining next to him; Simon Peter therefore motioned to him to ask Jesus of whom he was speaking. So while reclining next to Jesus, he asked him, "Lord, who is it?" Jesus answered, "It is the one to whom I give this piece of bread when I have dipped it in the dish." So when he had dipped the piece of bread, he gave it to Judas son of Simon Iscariot. After he received the piece of bread, Satan entered into him. Jesus said to him, "Do quickly what you are going to do." Now no one at the table knew why he said this to him. Some thought that, because Judas had the common purse, Jesus was telling him, "Buy what we need for the festival"; or, that he should give something to the poor. So, after receiving the piece of bread, he immediately went out. And it was night.
When he had gone out, Jesus said, "Now the Son of Man has been glorified, and God has been glorified in him. If God has been glorified in him, God will also glorify him in himself and will glorify him at once. Little children, I am with you only a little longer. You will look for me; and as I said to the Jews so now I say to you, `Where I am going, you cannot come.' I give you a new commandment, that you love one another. Just as I have loved you, you also should love one another. By this everyone will know that you are my disciples, if you have love for one another."
St. John paints an interesting picture of the unfolding betrayal. Of the eleven faithful disciples, only St. Peter and the evangelist are initially aware of that Judas, the man from Kerioth, is about to betray the Master. In fact, the remaining nine seem to thing that the Teacher has sent their brother out on a charity, or chow run. No, this was hardly the case.
Judas, according to Matthew's account, had in fact already agreed to throw the master to his enemies and was paid well for the deed. Now, he simply had to work out the logistics of making sure that Caiaphas's goons would make it to the garden in time to collar the Christ.
There are volumes of apologetic works explaining or conjecturing just why Judas betrayed the Master but in truth, these are little more than thin whitewash. Both scripture, and Judas' own conduct would tell us a different story. Mr. Iscariot was motivated by the same things that tweak fallen humanity today: greed, recognition, fleeting fame, the list goes on.