[jer33 3]

The thief on the cross argument is not valid. He was not under the New Covenant when he died. There is the possibility he had been baptized by John. But the most important point is that Jesus had the power to forgive sin while on this earth.

Jesus Christ died before the thief on the cross.

[jkl1122]

But Jesus told the thief he would be with him in paradise before he died, therefore, he was saved at that point in time, not after Christ died. Also, the thief obviously died before Christ was buried and resurrected, and since we are baptized into Christ's death and raised like his resurrection (Romans 6:3-4), that baptism could not have been in effect until after the resurrection.