The time when the thief was saved was the hour of our Lord's greatest weakness. He was hanging in agony on the cross. Yet even then He heard and granted a sinner's petition and opened to him the way of eternal life (Luke 23:39). Surely this was power!
The man whom our Lord saved was a wicked sinner at the point of death with nothing in his past life to recommend him, and nothing notable in his present position but a humble prayer. Yet even he was yanked from the fire. Surely this was "mercy."
Do we want proof that salvation is by grace and not by works? We see it here. The dying thief was nailed hand and foot to the cross. He could do literally nothing for his own soul. Yet even he, through Christ's infinite grace, was saved. No one ever received such a strong assurance of his own forgiveness as this man.
Do we want proof that sacraments and ordinances are absolutely not required for salvation, and that men may be saved without them when they cannot be had? We have it here. The dying thief was never baptized, belonged to no visible church, and never received the Lord's supper. But he repented and believed, and therefore he was saved.
We see, lastly, in the history before us, how near a dying believer is to rest and glory. We read that our Lord said to the malefactor in reply to his prayer, "Today you shall be with me in paradise."
That word today tells us that the very moment a believer dies, his soul is in happiness and in safe keeping. His full redemption is not yet come. His perfect bliss will not begin before the resurrection morning. But there is no delay, no season of suspense, no purgatory between his death and a state of reward. In the day that he breathes his last he goes to Paradise. In the hour that he departs he is with Christ (Philippians 1:23).
Adapted from The Gospel of Luke by J.C. Ryle (Chapter 23).