Judas was one of the closest disciples of Jesus from Nazareth. The inner circle (khavoora) of them comprised of 12 he called apostles (messengers). They were supposed to bring his teaching to the world. One of them betrayed him. The name Judas appears in English perhaps in order to differentiate him from Judah, one of Jesus' brothers. But, in fact, it is the same name. First it was given to one of patriarch Jacob's 12 sons. Only Judah's tribe survived til Jesus' times. Epistle to Hebrews (7:14) says:"For it is clear that our Lord descended from the tribe of Judah". That is why we call the modern Jewish people Jews and their religion - Judaism. Judas Iscariot ( his last name probably means the man from Krayot) was the only non Galilean among the disciples of Jesus. He might had felt isolated and sometimes even unwelcomed by the disciples. He was from the province of Judea. Perhaps he belonged to a most extreme wing among the religious group of Pharisees - Zealots. We have to note that among Jesus' disciple there was at least one zealot. He was called Simon the Zealot. Zealots were fanatical extreme people that were zealous for Jewish independence and freedom from foreign occupation by any price. They were expecting such a Messiah who would lead a revolt against Rome and reestablish the Kingdom of Judah.
The event of Judas' betrayal is attested in many places of the New Testament.
"Then Judas Iscariot, one of the Twelve, went to the chief priests to betray Jesus to them. They were delighted to hear this and promised to give him money. So he watched for an opportunity to hand him over."
"Now Judas, who betrayed him, knew the place, because Jesus had often met there with his disciples. So Judas came to the garden, guiding a detachment of soldiers and some officials from the chief priests and the Pharisees. They were carrying torches, lanterns and weapons."
"and said, “Brothers and sisters, the Scripture had to be fulfilled in which the Holy Spirit spoke long ago through David concerning Judas, who served as guide for those who arrested Jesus."
Possibly 1.Cor. 11:23,:
Paul, who was not a witness of these events, says:
"For I received from the Lord what I also passed on to you: The Lord Jesus, on the night he was betrayed, took bread..."
(It is possible that the meaning of the Greek word "betray"in the original version is that God is giving Jesus over to his suffering.)
Prof. Ehrman thinks "the common notion that Judas simply told the authorities where they could locate Jesus apart from the crowd may be right, but why would they need an insider for that kind of information?
Judas might have divulged something else, some information that the authorities could use to bring Jesus up on charges.
It is striking that in the reports of Jesus trials, he is charged with calling himself such things as the Messiah, the Son of God, and the King of the Jews. (Mark 14:61, 15:2, John 18:33, 19:19)
In the public teaching of Jesus... never calls himself such things. In the earliest source, when someone does calls him the messiah, he hushes it up. (Mark 8:30) Where did the authorities get the idea that he called himself such things? This might have been exactly what Judas betrayed to the authorities! We know that Jesus taught his disciples privately things that he did not say in public. Did Judas betray insider information?"
Bargil Pixner in his book "With Jesus in Jerusalem" says:
"... At the house of the high priest, very different deliberations were in progress. "The chief priests and the teachers of the law were looking for some slay way to arrest Jesus and kill him. "But not during the feast" or the people may riot". (Mark 14:1-2)Thus it was very convenient for them when a disciple of Jesus came to them and agreed to hand over this dangerous Galilean. They offered him thirty denarii for his plan.
What may have brought Judas to this action?
It was hardly his worry about money. Jesus' reproach at the meal in Bethany may have triggered thoughts of revenge in him. But the main rationale behind his action must have been something more profound...
I believe he was also - like his fellow Simon a Zealot, or was very closely connected to the Zealot movement or their way of thinking. After all, the other apostles were not very remote from this world of ideas, neither. Gradually, Judas realized that Jesus had no intention of fulfilling the Zealot's triumphal idea of the Messiah. This Jesus was too gentle for him and did not show any design of rising as a commander to lead the people of Israel against heathen supremacy into freedom. He was the one who rather shrank back from taking up arms; three times he speaks of his imminent death.... It was a pity, because this man possessed great miraculous power and the people ran after him. He, Judas, had to do something to rouse Jesus from lethargy...."
Prof. Bart D. Ehrman in his work "The Historical Jesus" objects the common idea about Judas betrayal:
"Jesus was almost certainly betrayed by one of his followers, Judas Iscariot. What is not clear, though, is what it was that Judas betrayed or why he acted as he did. It seems unlikely that he was hired simply to inform the authorities of Jesus' whereabouts, because they could have obtained this information without paying for it. The surviving traditions contain hints that Jesus may have divulged insider information that was available to him as one of the twelve disciples and that was used against Jesus at his trial."