He didn't need anyone to betray him. Why would he? He could have just turned himself in. The selfless act of offering oneself up as a sacrifice should have been right up his alley, but he didn't do that. Jesus did not want to be apprehended. He specifically hid from Roman troops looking for him. If he was really intent on becoming a martyr to die for our sins, he would have simply turned himself in to the authorities.
I must admit I have never really understood this either. From a theological point of view, if Jesus really
wanted to be captured, he could have just turned up at the Temple or wherever and given himself up to the guards. It doesn't make a whole lot of sense to me that a person should enter the city in triumph, make a scene in the Temple overturning tables, cause such a fuss that the High Priest decides he needs to be got rid of, and yet require one of his closest followers to identify him to the guards in order for an arrest to be made.
I assume that from the High Priest's point of view, doing it this was preferable. He could have had his men march through Jerusalem during the day, identify Jesus by asking people, and drag him off, but that would be a pretty incendiary act. Better to do it quietly at night, at which time they might indeed need somebody to lead them to him. From that point of view, the usefulness of Judas is clear. But if you believe that Jesus actually wanted this to happen, then it's not nearly so clear, because he would have been perfectly capable of giving himself up without needing Judas as a middle man. It seems that if you believe all of this was intended by Jesus, you must think that he actively wanted Judas to betray him, not merely wished to use the betrayal as an unfortunate but necessary element of his own Passion.
Didn't Jesus also say that the 12 disciples would be the judges of the 12 tribes of Israel? How are 11 disciples going to judge 12 tribes if Judas is condemned?
To be fair, he didn't say there would be one disciple per tribe. In fact it's not really certain whether there were actually twelve of them. Jesus certainly had lots of disciples (a lot more than twelve). "The Twelve" were the inner core, as it were. And it seems likely that Jesus called them "the Twelve" and that this had obvious symbolic importance. But it doesn't necessarily mean that there were literally twelve of them. The fact that the different Gospels can't agree on what their names were supports this. In which case, it probably wouldn't really matter if one disciple dropped out; "the Twelve" may have had fluctuating membership anyway even in Jesus' day.
He certainly hadn't been trying not to be noticed with his sermons. Which he knew were dangerous because of the power the Sadduces had.
The Sadducees weren't very powerful or indeed numerous. In any case, there was nothing particularly dangerous about Jesus' teachings, judging by the Gospels. He said much the same thing as many Pharisee teachers, and they didn't get physically attacked for it.
That's monophysitism, and also implying that the purpose of the trinity is to deceive.
Monophysitism is a doctrine about christology, not the Trinity (it's the view that Christ had only a single nature).
Side note: I never really understood why the Holy Spirit was considered separate from the Son, considering it's basically Jesus' ghost up in heaven.
No it's not! Jesus is supposed to be
resurrected, so he's not a ghost, he's a physical person. The Holy Spirit is a distinct divine person who is
sent by the Son but is not identical with him.