Did Judas Iscariot commit an unforgivable sin?
Yes, he did. His greed moved him to steal money that had been donated for a sacred use. He even pretended to be concerned about the poor when his real interest was to acquire more money to steal. (John 12:4-8) Once Judas’ heart had become permanently set in doing wrong, he betrayed Jesus for 30 pieces of silver. Jesus knew that Judas could never truly repent for what he had done, and he called him “the son of destruction.” (John 17:12) This meant that when Judas died, he would suffer permanent destruction, with no hope for a resurrection.—Mark 14:21.
However, they contradict themselves when they wrote before that "God has not authorized us to judge anyone—even ourselves.". On the other hand, the following two texts can absolve Judas:
When I was with them, I used to watch over them on account of your own name, which you have given me; and I have protected them, and not one of them is destroyed except the son of destruction, so that the scripture might be fulfilled. (John 17:12)
If the Scripture had to be fulfilled, Judas was an instrument for God's purposes, so he had no choice to do what he did.
Also, we read in Luke the following:
Then Satan entered into Judas, the one called Iscariot, who was numbered among the Twelve, and he went off and talked with the chief priests and temple captains about how to betray him to them. (Luke 22:3-4)
If Satan possessed Judas, he must be absolved because he was used by Satan as a puppet. God was guilty for permitting and invisible being to enter into a man.
Furthermore, most of what is written about Judas is fiction. This is another proof of the idiocy of Watchtower's theology.
I have written an article in Spanish about it http://jehovismo.com/en-defensa-de-judas/