John Lightfoot on Luke 23:42

[Lord, remember me.] Christ is now upon the cross, as of old Joseph was in the prison, between two malefactors. There one of them was delivered, the other hanged; here one obtains salvation, the other perisheth. The faith of this thief is admirable; and kept even pace with that of the apostles, if, in some circumstances, it did not go beyond it. The apostles acknowledged 'Jesus to be the Messiah'; and so doth he: with this addition, which I question whether they did so clearly own and know or no, viz., that Christ should reign and have his kingdom after his death. He seems to have a sounder judgment concerning Christ's kingdom than the apostles themselves, as may be gathered from their question, Acts 1:6.

It pleased God, in this last article of time, to glorify the riches of his grace in a singular and extraordinary manner, both in the conversion of a sinner and the forgiveness of his sins: I say in such an article of time which the world had never before seen, nor ever was like to see again; viz., in the very instant wherein the Messiah was finishing his redemption. It was not unknown to either of the thieves that Jesus was therefore condemned to die because he had professed himself 'the Christ'; hence that of the impenitent malefactor, "If thou art Christ, save thyself and us." And if the penitent thief did for a while join with the other in his petulant reproaches (which seems intimated to us Matthew 27:44), yet was his heart touched at length, and, perhaps, upon his observation of that miraculous darkness which at that time had covered the world.