‘Now at the feast he used to release to them one prisoner whom they asked of him. And there was one called Barabbas lying bound with those who had made insurrection, men who in the insurrection had killed.'
The custom of releasing an as yet unconvicted prisoner at the Passover seems to have been Pilate's own (‘he used to release') and is not evidenced outside the Gospels. But there is nothing intrinsically unlikely in it and there is evidence elsewhere of examples where prisoners were released to please crowds, and of amnesties given. It was therefore not unusual. It was regularly seen as a way of gaining popularity. He would see it as a sop to the people, and as an aid to maintaining the public peace. And the ensuing events support the idea of such a custom for it explains the presence of a crowd who had probably come for this very purpose. They would not have known about Jesus' arrest but they would certainly have known about the bound insurrectionists. The crowd would therefore appear to be of a type supportive of them, which helps to explain what follows.
‘There was one called Barabbas.' This is an unusual Greek phrase as it stands, for we would have expected another name prior to it (compare Matthew 26:3; John 9:11 but note Luke 22:47, although there it is specific). In Matthew 27:16-17 some authorities add the name Jesus to Barabbas, and Origen (who rejected it on theological grounds) refers to very early manuscripts which contained it. The unlikelihood of this finding its way into a text, and the extreme likelihood that it would be excised by devout Christian copyists, is in its favour and it may well be that originally this read ‘Jesus who is called Barabbas'. But there is no evidence for it ever having been in Mark in the manuscript that we possess.
It is made clear that Barabbas and his fellow-insurrectionists were murderers, probably seen as patriots by certain of the Jews as they would be seen as having acted against the Romans in the name of God. It was from such as these that many expected the Messiah to come. They would thus have a certain amount of popular support among the more belligerent. And this crowd were mainly of that type.