The Roman government had already condemned him to death by crucifixion. Because Jesus took his place on the cross. In fact, Christ was Barabbas's substitute both physically and spiritually. The doctrine of substitution describes both the nature of Christ's death and the method God uses in providing salvation for all of us. The guilt of the sinner is never denied.
Substitution is taught in the Bible in a variety of ways.
There are six steps involved in making a sacrifice. The first three steps were taken by the sinner for whom the sacrifice was being made. He selected and presented the proper sacrificial animal, Lev. He identified with the sacrifice by placing his hand on its head, Lev. Then, he killed the animal, Lev.