This will almost always come up at some point in a discussion on the necessity of baptism. Many times it gets thrown in after several passages have been cited to establish the biblical teaching on baptism. In the face of the multiplicity of passages that establish the necessity of baptism, the opponent will say something like, “well, the thief on the cross wasn’t baptized!”

The most a person can do in regards to whether the thief was baptized or not is to speculate. That is, to say whether
he was or he wasn’t baptized is pure speculation! I don’t know about you, but the condition of my immortal soul is too important to me to leave up to speculation. But, if we are going to speculate about whether the thief was baptized
or not, we should at least try to provide some evidence for our speculation.

My personal opinion on the thief is that he had been baptized. Now, let me provide some evidence for my speculation on this point. First, the thief lived at a time when John was baptizing so many people that it was said, “all Judea” was being baptized (Mark 1:5). When Jesus began His ministry it says that He baptized even more than John did (John 3:22, 26; 4:1, 2). So, there were a lot of people being baptized! Second, John and Jesus were both preaching a baptism of repentance (Luke 3:3; Matt. 3:8; 4:17). The thief may have been on the cross because of his repentance! Third, the thief knew Jesus was innocent (Luke 23:41). How could he have known that unless he already knew who Jesus was? Fourth, he addressed Jesus as a disciple would, calling Him Lord (Luke 23:42). Fifth, he asked Jesus to remember him when He came into His
kingdom (Luke 23:42). How would the thief know anything about a kingdom unless he already knew who Jesus was?
Why would he expect that Jesus would be able to remember him at all, considering that Jesus was dying on the cross?
It is very obvious, from what the thief said, that he already knew Jesus before the scene on the cross! Now, where is
your evidence that he was not baptized?

Ultimately, though, the entire question is irrelevant. Jesus had power on earth to forgive sins (Matt. 9:6). The thief lived and died under the Law of Moses, before the Great Commission was given (Matt. 28:18-20), before the church was established (Acts 2:38, 41, 47). Jesus was physically present with the thief to tell him personally that he would be with Him in paradise (Luke 23:43). You’re not hanging on a cross next to Jesus, you’re living in the world after Jesus has ascended back to haven. You can’t do what the thief did physically hanging on a cross next to Jesus! You must do
what Jesus said before He departed this world (Mark 16:16). You must be baptized into Christ for the remission of your sins! (Acts 2:38; Rom. 6:3, 4; Gal. 3:26, 27; 1 Pet. 3:21).