What follows is a quote from Calvin's commentary on Luke 23:42-43, "Then he said, 'Jesus, remember me when you come into your kingdom.' Jesus answered him, 'Truly I tell you, today you will be with me in paradise.'" It is longer than most quotes I post but I think it is an excellent analysis of the passage by Calvin. The Reformer expands here on the Thief's salvation through faith alone.
Though Christ had not yet made a public triumph over death, still he displays the efficacy and fruit of his death in the midst of his humiliation. And in this way he shows that he never was deprived of the power of his kingdom; for nothing more lofty or magnificent belongs to a divine King, than to restore life to the dead. So then, Christ, although, struck by the hand of God, he appeared to be a man utterly abandoned, yet as he did not cease to be the Savior of the world, he was always endued with heavenly power for fulfilling his office. And, first, we ought to observe his inconceivable readiness in so kindly receiving the robber without delay, and promising to make him a partaker of a happy life. There is therefore no room to doubt that he is prepared to admit into his kingdom all, without exception, who shall apply to him. Hence we may conclude with certainty that we shall be saved, provided that he remember us; and it is impossible that he shall forget those who commit to him their salvation.
But if a robber found the entrance into heaven so easy, because, while he beheld on all sides ground for total despair, he relied on the grace of Christ; much more will Christ, who has now vanquished death, stretch out his hand to us from his throne, to admit us to be partakers of life. For since Christ has, “nailed to his cross the handwriting which was opposed to us, (Colossians 2:14,) and has destroyed death and Satan, and in his resurrection has triumphed over the prince of the world, (John 12:31,) it would be unreasonable to suppose that the passage from death to life will be more laborious and difficult to us than to the robber. Whoever then in dying shall commit to Christ, in true faith, the keeping of his soul, will not be long detained or allowed to languish in suspense; but Christ will meet his prayer with the same kindness which he exercised towards the robber. Away, then, with that detestable contrivance of the Sophists about retaining the punishment when the guilt is removed; for we see how Christ, in acquitting him from condemnation, frees him also from punishment. Nor is this inconsistent with the fact, that the robber nevertheless endures to the very last the punishment which had been pronounced upon him; for we must not here imagine any compensation which serves the purpose of satisfaction for appeasing the judgment of God, (as the Sophists dream,) but the Lord merely trains his elect by corporal punishments to displeasure and hatred of sin. Thus, when the robber has been brought by fatherly discipline to self-denial Christ receives him, as it were, into his bosom, and does not send him away to the fire of purgatory.
We ought likewise to observe by what keys the gate of heaven was opened to the robber; for neither papal confession nor satisfactions are here taken into account, but Christ is satisfied with repentance and faith, so as to receive him willingly when he comes to him. And this confirms more fully what I formerly suggested, that if any man disdain to abide by the footsteps of the robber, and to follow in his path, he deserves everlasting destruction, because by wicked pride he shuts against himself the gate of heaven. And, certainly, as Christ has given to all of us, in the person of the robber, a general pledge of obtaining forgiveness, so, on the other hand, he has bestowed on this wretched man such distinguished honor, in order that, laying aside our own glory, we may glory in nothing but the mercy of God alone. If each of us shall truly and seriously examine the subject, we shall find abundant reason to be ashamed of the prodigious mass of our crimes, so that we shall not be offended at having for our guide and leader a poor wretch, who obtained salvation by free grace.
-John Calvin, Commentaries