Jesus warned His disciples that one of them would betray Him and all of His disciples assured Him that they would not and yet, Judas was identified as the one to betray Christ. Satan entered into Judas and he betrayed Christ when he identified Christ to those who wanted to kill Him by giving Jesus a kiss.
Jesus knew Judas was going to betray Him before it happened and made a comment while washing His disciples feet that indicated that He knew:
John 13:5 After that he poureth water into a bason, and began to wash the disciples' feet, and to wipe them with the towel wherewith he was girded.
John 13:6 Then cometh he to Simon Peter: and Peter saith unto him, Lord, dost thou wash my feet?
John 13:7 Jesus answered and said unto him, What I do thou knowest not now; but thou shalt know hereafter.
John 13:8 Peter saith unto him, Thou shalt never wash my feet. Jesus answered him, If I wash thee not, thou hast no part with me.
John 13:9 Simon Peter saith unto him, Lord, not my feet only, but also my hands and my head.
John 13:10 Jesus saith to him, He that is washed needeth not save to wash his feet, but is clean every whit: and ye are clean, but not all.
John 13:11 For he knew who should betray him; therefore said he, Ye are not all clean.
At Passover, Jesus gave another clue to His disciples who it was that would betray Him by dipping His bread in the sop and giving it to Judas but the disciples did not realize it at the time. Once Judas received it, Satan entered him and he left the dinner.
John 13:18 I speak not of you all: I know whom I have chosen: but that the scripture may be fulfilled, He that eateth bread with me hath lifted up his heel against me.
John 13:19 Now I tell you before it come, that, when it is come to pass, ye may believe that I am he.
John 13:20 Verily, verily, I say unto you, He that receiveth whomsoever I send receiveth me; and he that receiveth me receiveth him that sent me.
John 13:21 When Jesus had thus said, he was troubled in spirit, and testified, and said, Verily, verily, I say unto you, that one of you shall betray me.
John 13:22 Then the disciples looked one on another, doubting of whom he spake.
John 13:23 Now there was leaning on Jesus' bosom one of his disciples, whom Jesus loved.
John 13:24 Simon Peter therefore beckoned to him, that he should ask who it should be of whom he spake.
John 13:25 He then lying on Jesus' breast saith unto him, Lord, who is it?
John 13:26 Jesus answered, He it is, to whom I shall give a sop, when I have dipped it. And when he had dipped the sop, he gave it to Judas Iscariot, the son of Simon.
John 13:27 And after the sop Satan entered into him. Then said Jesus unto him, That thou doest, do quickly.
John 13:28 Now no man at the table knew for what intent he spake this unto him.
John 13:29 For some of them thought, because Judas had the bag, that Jesus had said unto him, Buy those things that we have need of against the feast; or, that he should give something to the poor.
John 13:30 He then having received the sop went immediately out: and it was night.
John 13:31 Therefore, when he was gone out, Jesus said, Now is the Son of man glorified, and God is glorified in him.
John 13:32 If God be glorified in him, God shall also glorify him in himself, and shall straightway glorify him.
John 13:33 Little children, yet a little while I am with you. Ye shall seek me: and as I said unto the Jews, Whither I go, ye cannot come; so now I say to you.
When Judas approached Christ he was accompanied by a band of men and officers (sent by the chief priests and the scribes and the elders) who were armed with swords and staves with evil intentions to kill Jesus.
John 18:2 And Judas also, which betrayed him, knew the place: for Jesus ofttimes resorted thither with his disciples.
John 18:3 Judas then, having received a band of men and officers from the chief priests and Pharisees, cometh thither with lanterns and torches and weapons.
John 18:4 Jesus therefore, knowing all things that should come upon him, went forth, and said unto them, Whom seek ye?
John 18:5 They answered him, Jesus of Nazareth. Jesus saith unto them, I am he. And Judas also, which betrayed him, stood with them.
John 18:6 As soon then as he had said unto them, I am he, they went backward, and fell to the ground.
John 18:7 Then asked he them again, Whom seek ye? And they said, Jesus of Nazareth.
John 18:8 Jesus answered, I have told you that I am he: if therefore ye seek me, let these go their way:
John 18:9 That the saying might be fulfilled, which he spake, Of them which thou gavest me have I lost none.
John 18:10 Then Simon Peter having a sword drew it, and smote the high priest's servant, and cut off his right ear. The servant's name was Malchus.
John 18:11 Then said Jesus unto Peter, Put up thy sword into the sheath: the cup which my Father hath given me, shall I not drink it?
John 18:12 Then the band and the captain and officers of the Jews took Jesus, and bound him,
John 18:13 And led him away to Annas first; for he was father in law to Caiaphas, which was the high priest that same year.
Judas kiss was also described by Mark who went into details regarding the conversation Judas had with those who were with him and sought to kill Jesus. Judas told them that when he kissed Jesus they were to take Jesus and lead him away safely. Then Judas approached Jesus, saying "Master, master" and kissed Him.
And immediately, while he yet spake, cometh Judas, one of the twelve, and with him a great multitude with swords and staves, from the chief priests and the scribes and the elders. Mark 14:43
And he that betrayed him had given them a token, saying, Whomsoever I shall kiss, that same is he;take him, and lead him away safely. Mark 14:44
And as soon as he was come, he goeth straghtway to him, and saith, Master, master; and kissed him. Mark 14: 45
Jesus referred to Judas as the Son of Perdition:
John 17:12 While I was with them in the world, I kept them in thy name: those that thou gavest me I have kept, and none of them is lost, but the son of perdition; that the scripture might be fulfilled.