The Thief Did More Than Believe
He had minutes left and no hands free. Count what he did with them.
The thief on the cross is the standing proof that salvation is by faith alone, with no works, no baptism, no time to do anything. He is brought out in every argument about the sinner's prayer: a man who did nothing but believe, and went to paradise that day. I agree with the conclusion. He was not saved by anything he earned; he had nothing to earn it with. But read the five verses slowly, and count. In one breath, nailed to a beam, he did at least six things, and every one of them is something Scripture elsewhere calls saving faith doing what it does. He is not the proof that faith does nothing. He is the proof that living faith cannot help acting even when it has no hands.
The five verses
"And one of the malefactors which were hanged railed on him, saying, If thou be Christ, save thyself and us. But the other answering rebuked him, saying, Dost not thou fear God, seeing thou art in the same condemnation? And we indeed justly; for we receive the due reward of our deeds: but this man hath done nothing amiss. And he said unto Jesus, Lord, remember me when thou comest into thy kingdom. And Jesus said unto him, Verily I say unto thee, To day shalt thou be with me in paradise." (Luke 23:39-43).
What he did
He changed. The first thing to notice is easy to miss because Luke does not report it. Matthew and Mark do. "The thieves also, which were crucified with him, cast the same in his teeth." (Matthew 27:44); "Let Christ the King of Israel descend now from the cross, that we may see and believe. And they that were crucified with him reviled him." (Mark 15:32). Thieves, plural. Both of them started out mocking Him. Somewhere in those hours one of them turned, and Luke picks the story up after the turn. So the thief is not a man who happened to believe. He is a man who repented, in the plainest sense of the word, on a cross, with the other thief still mocking beside him to show what he had been an hour before (see Repentance).
He feared God. "Dost not thou fear God?" That is his first recorded word after the turn, and it is the first thing Scripture says wisdom is: "The fear of the LORD is the beginning of wisdom: and the knowledge of the holy is understanding." (Proverbs 9:10). He is dying under Rome's sentence and the thing he is afraid of is not Rome.
He confessed his own guilt. "We indeed justly; for we receive the due reward of our deeds." No excuse, no plea about a hard life. The publican's prayer, in a criminal's mouth: "And the publican, standing afar off, would not lift up so much as his eyes unto heaven, but smote upon his breast, saying, God be merciful to me a sinner." (Luke 18:13). "He that covereth his sins shall not prosper: but whoso confesseth and forsaketh them shall have mercy." (Proverbs 28:13). "The sacrifices of God are a broken spirit: a broken and a contrite heart, O God, thou wilt not despise." (Psalm 51:17). He had the broken spirit, and he said so out loud.
He rebuked sin. He did not only stop mocking; he turned to the man still doing it and told him to stop. That is not the act of a man minding his own salvation. It is the act of a man who now sees mocking Christ as the thing that ought to frighten anyone, and says so to the only neighbor he has left.
He defended the innocent. "This man hath done nothing amiss." Consider where he said it. The priests were mocking, the soldiers were mocking, the crowd was mocking, and the one voice raised for Jesus's innocence in the whole of Golgotha came from a condemned thief with nothing to gain by it. Pilate had said the same thing three times and washed his hands. The thief said it once and meant it, at the cost of the last goodwill he had from the man beside him. "Whosoever therefore shall confess me before men, him will I confess also before my Father which is in heaven." (Matthew 10:32, and the next verse is the same promise turned over: "But whosoever shall deny me before men, him will I also deny before my Father which is in heaven" (Matthew 10:33)). The rulers in John 12 believed and would not confess Him "lest they should be put out of the synagogue" (John 12:42). The thief believed and confessed Him from a cross.
He called Him Lord and King. "Lord, remember me when thou comest into thy kingdom." Read what that sentence assumes. The man beside him is dying. The thief calls Him Lord anyway, and speaks of His kingdom as a thing still coming, which means he believed in a King who would outlive His own execution. That is more resurrection faith than the apostles had that afternoon. Paul's formula is "That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved." (Romans 10:9), and the thief did both halves before the resurrection had happened, with the body of the Lord he was confessing hanging in front of him. This was not "accepting Jesus." It was Lordship, said out loud at the one moment it looked most absurd (see Lord, or Just Savior?).
He asked. "Remember me." Not save me, not take me down. Remember me. He asked for the one thing a king can give a condemned man, which is to be known by him when the kingdom comes. And he got more than he asked: "And Jesus said unto him, Verily I say unto thee, To day shalt thou be with me in paradise." (Luke 23:43).
What this does not prove
It does not prove works earn anything. The thief had no deeds to bring; his "due reward" was death, and he said so. Grace went first, all the way. It does not prove baptism is required for salvation, and it does not prove it is optional either; he could not get to water, and the New Testament never treats a man kept from an ordinance by force as though he refused it. And it does not prove a man can be saved with no repentance, no confession, no fear of God, no lordship, and no public word for Christ, because the thief had all five in one sentence. The man who cites him to prove that a silent private decision saves has cited the wrong man. If you want the thief on the cross for your doctrine, take all of him.
Where this lands
The devils believe, and tremble (James 2:19). The thief believed, and feared God, and confessed, and rebuked, and defended, and called Him Lord, and asked. That is the difference between belief that agrees and belief that moves, and he had no hands and no feet and did it with his mouth in the time he had (see Faith Is a Verb and Believe Into Christ). Isaiah had said the Servant would be "Therefore will I divide him a portion with the great, and he shall divide the spoil with the strong; because he hath poured out his soul unto death: and he was numbered with the transgressors; and he bare the sin of many, and made intercession for the transgressors." (Isaiah 53:12). Numbered with the transgressors, and interceding for them. One of them, that day, heard the intercession and answered it. Nobody has ever had less time or less to offer. Nobody has ever had less excuse to do nothing.
Related: No Man Plucks Them, When Grace Becomes a License, Faith Is a Verb, Believe Into Christ, Lord, or Just Savior?, Repentance, The First Shall Be Last, and Heaven. Scripture from the King James Version, linked to BibleHub; the words of Christ are marked in purple and the words of God in gold.