Part 1 is available here.
AP: What shall we say about the historicity of Judas? Some scholars believe that the character/person of Judas is weighed down by legends and improbabilities, so much so that they say Judas probably never existed. If that's true, then the early communities of Jesus followers totally invented him. And why would they do that? In order to place the burden of Jesus' death upon his shoulders. Again, that's just what some scholars say.
There is, however, another option. If we examine this issue a little more closely, we might find some arguments that favor the historicity of this individual, based on the criteria of authenticity or general tools that help us gauge the possibility of the historicity of the facts and sayings of Jesus. I think it is very plausible that the figure of Judas is not a mere invention of the Christian community. What follows are the reasons why I think it likely he existed.
First is the criterion of multiple attestation. We have two independent sources–Mark and John–attest to his existence. There may even be a third independent tradition, if we consider the fanciful account of the death of Judas in Acts 1:18-19 as history turned legend; i.e., we could not have the story of his death (not even one turned into a legend), if he did not exist. So, his historical existence is attested to by two or three different sources.
Second is the criterion of difficulty. It seems unlikely that the primitive community invented the character of the traitor out of thin air. Under the hypothesis of that Judas is but pure fiction, the moments of the "invention" of this figure corresponds to a time frame in which the community believed that Jesus was at least semi-divine, omniscient, endowed with all wisdom. Attributing a case of such crass ignorance or foresight casts him in an unfavorable light. And so it seems unlikely. What proof is there? Well, the tradition had to invent the idea that Jesus foresaw, as a divine prophet, the betrayal of Judas (Matt. 17:22) and even wished that he had not been born. It also invented, as we said, how the "delivery" or betrayal of Judas is a fulfillment of the Scriptures, part of the divine plan of salvation and was announced beforehand.
Third, when a new character is invented, he is usually surrounded with more full and developed features. An analysis of the traditions, though, shows something different going on. Like a snowball, details about Judas just seem to grow and grow. The original presentation was that Judas existed and that he was one of the so-called "Twelve." The various lines of tradition developed around that idea. It was later added that he had a problem with greed, as were the legendary details surrounding his betrayal and death. We can see the difference/growth from the Synoptics to the Gospel of John, or by comparing Matthew to Acts.