To begin with lets review a bit of bible history, for those of you who are not familiar with the story of Judas Iscariot. Judas betrayed Jesus christ to the chief priests and elders for 30 silver pieces, Judas then felt so horrible for what he had done when he found out that Jesus had been condemned, he attempted to return the silver pieces, but the chief priests and elders refused to accept them from him. Judas threw down the silver pieces in the temple, and departed, he then hung himself.
Now there are many beliefs as to how exactly Judas becomes a vampire, the first belief and most common is that god cursed Judas and his family to walk the earth until the second coming of Jesus, and until that time he would thirst for the blood of jesus, which of course he could only receive through christians. Which is proof that perhaps this myth was propogated by the church.
The second belief is not as common, but goes along with the Last Supper, what many do not understand is that during the last supper jesus was quite literal when he said to drink of his blood and eat of his flesh, in fact half of his disciples walked out on him when this happened. There are quite a few people who belief Jesus himself was a vampire, thus it is easily believed that Jesus himself created Judas knowing he would betray him, and perhaps created Judas as a grand experiment.
It has been very common belief throughout most vampire folklore that those who commit suicide or die and untimely death can or will become vampires themselves. This was especially prevalent during the dark ages and middle ages in the catholic church, in christianity those who commit suicide are believed to be damned to hell (it was only during the dark ages that the idea of purgatory was introduced). This belief, lends them to the belief that Judas is damned, not only for his betrayal, but for taking his own life.
In many cultures a common folklore belief about vampires was the presence of red hair. In most of the meditteranian region, those with red hair were believed to be vampires, or would die to become vampires, red hair afterall was incredibly uncommon in this area. Judas was said to have been a red head thus it was believed his children would also have red hair, this is where the idea that all vampires created by Judas have red hair. It is very possible this belief came into play after the original myth was created as cultural folklore was included.
Perhaps the most common of the vampire mythos is the belief that a vampire can be destroyed by a stake, more precisely a stake of aspen wood. Aspen is the wood that it is believed the cross upon which Jesus died was made of. It was believed that because Judas had ultimately caused Jesus' death he would be repelled by the item of his demise.
It is also believed that the mythos of a vampires repulsion by crucifixes and other holy items stems from the Judas mythos. Simply put, Judas felt great sadness for what he had done, and as such he was repelled by anything that reminded him of his great crime, and the atrocities which he committed.
The final folk belief about vampires that is attributed to the Judas Iscariot mythos is the belief that vampires are repelled by silver. It is believed that since Judas himself cast aside the silver which he had taken when he sold out jesus that he now had a repulsion to the substance and as such was repelled by it.
The specific quote from the bible is as such:
Then Judas, which had betrayed him, when he saw that he was condemned, repented himself, and brought again the thirty pieces of silver to the chief priests and elders, 4 Saying, I have sinned in that I have betrayed the innocent blood. And they said, What is that to us? see thou to that. 5 And he cast down the pieces of silver in the temple, and departed, and went and hanged himsef. (Matthew 27:3-5)
This myth is very obscure, it is old, and not as popular as many other myths, but it gives answers to why a few of the folklore beliefs exist. During the modern day the image of the vampire has changed, from a predatory creature of the night, to a almost romantic figure of modern culture. Perhaps this is why many origin myths have survived while others died out, there is a great deal less involvement by the Church in our beliefs and as such many of the truely religous vampire beliefs have all but died out.
In reality, most vampire beliefs were created by the Church to keep people from robbing graves, roaming the streets at night, and to generally instill fear in a relatively ignorant populace. And it is quite safe to say that the majority of our populace is far from ignorant, and as such, through novels and books the image of the vampire has become romanticized and glamorized.