Verse 27. - And with him they crucify two robbers (λησταί) - not "thieves" (κλέπται); St. Luke (Luke 23:32) shows that these two robbers formed a part of the procession to Calvary; but they were crucified after our Lord - one on his right hand, and one on his left. We know from St. Luke (Luke 23:40) that one of these malefactors was saved; while it would appear that the other died in his sins. And thus Christ upon his cross, between these two men, and with the title of King over his head, presented a striking and awful picture of the final judgment. Such is the view of St. Ambrose on St. Luke 22, and of St. Augustine, who says," This cross, if you mark it well, was a judgment-seat. For the Judge being placed in the midst, the one who believed was set free; the other who reviled him was condemned; and thus he signified what he will do with the quick and the dead. Some he will place on his right hand, and some on his left" (Augustine, Tract. 31 in S. Johan.).
15:22-32 The place where our Lord Jesus was crucified, was called the place of a scull; it was the common place of execution; for he was in all respects numbered with the transgressors. Whenever we look unto Christ crucified, we must remember what was written over his head; he is a King, and we must give up ourselves to be his subjects, as Israelites indeed. They crucified two thieves with him, and him in the midst; they thereby intended him great dishonour. But it was foretold that he should be numbered with the transgressors, because he was made sin for us. Even those who passed by railed at him. They told him to come down from the cross, and they would believe; but they did not believe, though he gave them a more convincing sign when he came up from the grave. With what earnestness will the man who firmly believes the truth, as made known by the sufferings of Christ, seek for salvation! With what gratitude will he receive the dawning hope of forgiveness and eternal life, as purchased for him by the sufferings and death of the Son of God! and with what godly sorrow will he mourn over the sins which crucified the Lord of glory!
the one on his right hand, and the other on his left; as if he had been one of them, and a principal among them; See Gill on Matthew 27:38.