In Luke 23:43, Jesus Christ told the penitent criminal crucified beside him, “Assuredly, I say to you, today you will be with me in Paradise” without mentioning his need to be baptized.
Jesus’ words to the penitent criminal crucified on the cross beside His (Luke 23:43) were said before the death of our Lord and therefore before He declared His definitive commandment to baptize in the Name of the Father, the Son and the Holy Spirit (Matthew 28:18-20) and before the coming of the Holy Spirit’s inspiring the apostle Peter’s first sermon with the commandment of the church age that all sinners repent and be baptised for the remission of their sins (Acts 2:38).
Before Jesus’ resurrection from the dead which evidenced Him to be God’s Son (Romans 1:1-4), the Law of Moses was operative for Jews while Gentiles were covered by “the law written in their hearts” (Romans 2:12-16), both of which did not require baptism for salvation. The penitent criminal was under no command to be baptised for salvation when Jesus promised him, “Assuredly, I say to you, today you will be with me in Paradise.” (Luke 23:43).
Also, this promise was given in a time of transition just after John the Baptist introduced “baptism of repentance for the remission of sins” (Mark 1:4) to the Jews and Jesus continued this practice (John 3:22). Then, the power to forgive sins belonged to Jesus as Deity (Matthew 9:1-8 especially verse 6; Mark 2:1-12 especially verse 10). Jesus’ “power on earth to forgive sons” is also necessarily implied in His settling of the case of the woman caught in adultary (John 8:1-11).
By his words to the second criminal and to Jesus when the three men hung dying on Roman crosses (Luke 23:40-42), the penitent criminal evidenced repentance and belief in Jesus Christ as the coming King. He may be among the very many from Judea and its surroundings who had been baptised by John the Baptist or Jesus’ disciples (Mark 1:4-5; John 3:22 to 4:2). However, it is not necessary to thus “argue from silence” in his case as Jesus Himself had promised that he would be in Paradise with Him that same day, necessarily implying he was saved,- having been baptized before being crucified or not.
If we,- like the penitent criminal,- believe in Jesus as God’s only-begotten Son and thus as authoritative especially as regards sinners’ salvation (John 3:34-36), today we must obey His command to be baptized for our eternal salvation (Mark 16:15-16). By Jesus’ authority, the penitent criminal need not be baptized and by that same authority, after His resurrection, the rest of us must, as He commanded, be baptized in order to be saved (1 Peter 3:21).
1 Peter 3:21 21There is also an antitype which now saves us—baptism (not the removal of the filth of the flesh, but the answer of a good conscience toward God), through the resurrection of Jesus Christ