In the parallel account in Mark we read:
"And when they could not come near Him because of the crowd, they uncovered the roof where He was. So when they had broken through, they let down the bed on which the paralytic was lying. When Jesus saw their faith, He said to the paralytic, 'Son, your sins are forgiven you.'" (Mark 2:4,5)
In this case there was a genuine expression of faith.
Which underscores the point, of those at the cross, if they believed on Christ then they would receive forgiveness of their sins. Not until.
I'm not sure why you continue to kick against the testimony of Scripture? What does it serve to insist that those who are not in Christ may not have had one sin charged to their account?
I guess Jesus was not omnipotent. His ability to forgive men was conditional upon their ability to see their sin and repent of it?
Jesus called upon his Father to forgive them "for they know not what they do." Now you have two possibilities. Either they knew what they were doing, and thus Jesus was a liar, or they did not know what they were doing, and Jesus forgave them.
It's your choice.
I think we've beaten this horse to death. The bible says it, I believe it, that settles it.