Answer:

The person who repented on the cross is not a particularly helpful example for your question for a couple of reasons.  First of all, this happened before Jesus had died and been resurrected.  Before the death and resurrection of Jesus, New Testament baptism did not exist, nor would it have had any meaning.  As we read in Romans 6:1-7, baptism is a participation in the death, burial and resurrection of Christ, which had not even happened when the criminal next to Christ repented.  Jesus did not send the Holy Spirit that we receive upon conversion until after he was resurrected from the dead.

Second, this person clearly could  not have been baptized, even if it were a relevant thing to do (it was not, but…).  Again, this makes this person quite unlike all of us, who are perfectly able to be baptized.  He was already nailed to a cross, and incapable of being baptized.  What God will do for those who, literally, are unable to be baptized at all is a matter for God to decide, not us, but in any case, this clearly does not apply to any of us. Only a very tiny fraction of people are unable to be baptized/immersed for health reasons. But this is not what you are inquiring about.

Let me add a third thing, which is that Jesus is capable of forgiving the sins of an individual if he so chooses.  This is his prerogative.  He did this for the man dropped through the roof in Luke 5:17-39.  Jesus can forgive the sins of whoever he chooses, but this clearly is a special case and is not relevant to us now.  Bringing up the criminal on the cross who appealed to Jesus adds confusion, not clarity, to this question.

Having shown that your example is not relevant to your question, let me get down to answering your actual question, which is what will happen to those who willfully choose not to be baptized into Christ for forgiveness of sins. Let me use the example of Acts 2:36-41.  These people asked what they must do to be saved.  They were instructed to repent and to be baptized.  They would then be forgiven of their sins and receive the gift of the Holy Spirit.  This is what Peter told those who asked. What if they chose not to repent?  What if they chose not to be baptized?  Then I HAVE to assume that they would not have been forgiven of their sins and would not have received the gift of the Holy Spirit.  I assume that the same applies to us today.  If we do not repent of our sins and submit to being baptized into Christ (Gal 3:26, Romans 6:1-7), then we will not be in Christ, we will not be forgiven, we will not receive the indwelling Holy Spirit, and we will not be saved.  This is about as clear as can be from the biblical mandate.  If we refuse when commanded by God to do something, then the promise attached to that thing does not apply to us.  I understand that some teach differently on this.  They teach that we are saved when we “accept Christ,”, but this is not what is taught in Scripture, and I refuse to teach anything other than what is taught in the Scripture.  If God intends to make an “exception,” that us up to him, but all I can do is read and apply the Bible, and the Bible is clear that we come into Christ when we are baptized into Christ, and not before.  Those who use the criminal on the cross are simply giving an irrelevant example, which simply confuses the question unnecessarily for the reasons I already gave.

John Oakes