FAQ on the Christian Faith
At that time, all Jews were waiting for the Messiah who God has foretold. Therefore, they knew well about "the Law and the sacrificial system," which God has given through Moses, more than any another people. They believed that the Messiah would come according to the law of God, and would free them from all their sins.
However, they did not believe the fact the baptism of Jesus by John Baptist was from God and was to lay all the sins of the world on Jesus (Mark 11: 27-33), but rather considered Him as a man who led the people astray and thus crucified Him.
Since Romans were protected from being scourged or crucified by the Roman law (Acts 22:25-29, 23:27), we can know that the thieves on the Cross were not Romans, but Jews. We can also know that the thief was a Jew who feared God from his words, saying, "Lord, remember me when You come into Your kingdom" (Luke 23:42) because the gospel of the kingdom of heaven was not preached to the Gentiles until the Peter preached the gospel to them (Acts 10:1-11:18). The thief already knew the Law and the sacrificial system, which God gave to Moses. So he believed that the Messiah would come according to the law of God.
He who comes to God must confess that he is a sinner, destined to go to hell for his sin. The thief confessed his sins, saying, "And we indeed justly, for we receive the due reward of our deeds" (Luke 23:41). We can also know that the thief feared God and his hope was in the kingdom of heaven from his words, saying, "Lord, remember me when You come into Your kingdom" (Luke 23:42).
He said, "But this Man has nothing wrong" (Luke 23:41). What did the thief know about what Jesus did? He believed that Jesus was conceived by the Holy Spirit, was born of the virgin Mary, was baptized by John the Baptist, the representative of mankind, took away all the sins of the world, and was crucified. He was a Jew who believed what Jesus did in his heart, even though he was crucified to receive the due reward of his deeds on the earth.
Those who confessed their sins through the baptism of John acknowledged God's justice when they heard all their sins were laid on Jesus through His baptism. However, those who didn't receive John's baptism of repentance rejected the will of God for them because they didn't believe in the baptism of Jesus, either (Luke 7:28-30).
On the contrary, the thief who was saved confessed that everything that Jesus did was correct and righteous while the other Jews didn't. He could say that Jesus was righteous because he confessed his sins through the baptism of John and believed that Jesus took away all his sins through His baptism. Accordingly, he could be saved. He was also a man who believed in the gospel of water and the Spirit. Because God is just, He justifies those who believe in the baptism of Jesus and the Cross according to His law.