Fatalistically Barabbas was unable to have a God. So when he got acquitted and Jesus got crucified, he tried hard to believe, to behave like a Christian but failed miserably.
Lagerkvist portrayed Barabbas as a very dynamic character. Rational yet with a deep urge to believe. Aversive of society, yet kind in his unique way. Vindictive, but not when he is under attack. Confused but his heart is in the right place.
Lagerkvist explored Barabbas, along with some other fantastic character and that's also in only a very few pages, in a concise novel which moves, both emotionally and intellectually.
Barabbas is the acquitted; the man whose life was exchanged for that of Jesus of Nazareth, crucified upon the hill of Golgotha. Barabbas is a man condemned to have no god. "Christos Iesus" is carved on the disk suspended from his neck, but he cannot affirm his faith. He cannot pray. He can only say, "I want to believe." Translated from the Swedish by Alan Blair