Wither Barabbas existed or not is irrelevant. What is relevant is the shocking quality of G_D's love revealed in the story! Imagine Barabbas regaining his freedom as an unexpected "by product"  of Jesus' Passion! It's a reminder that G_D loves us because of who He is, not because of anything we do. His release must have been very dislocating to him at least. Perhaps he used this "second chance" to turn his life around. Those being released from prison may well be experiencing dislocation. Here's hoping that they will experience G_D's love as they re-enter society.