The Greek is a little stronger than ‘thieves’; it is ‘robbers.’ That doesn’t mean much to us today, but it is a term which more applies to violent thieves.
They seek to insult him, and treat him as the lowest of the low, a common criminal, but in fact it only serves to demonstrate that he was truly our representative. He died even among transgressors. He took our place. That is what he is: the Saviour of fallen men and women, and he identifies with us in our most criminal state on Calvary's cross. The superscription is true; the whole image and symbolism of his execution speaks truth. There is that dual meaning all the way through Calvary: the orchestration of God, the picture painted by Almighty God. But they didn't understand it.