Well, I also don’t believe in a heaven/hell afterlife. If I did… I would have to say no. I don’t believe that punishment has any value.
I would however consign him to some form of purgatory. Exactly what form this would take I don’t know. Perhaps I would do something similar to what Lumpy suggested - all the consequences of his crimes would be visible to him, his beliefs would carefully be shown to be wrong, and he would be forced to talk extensively with every person his actions ever wronged or influenced, or whom he felt he was wronged by. This is just a suggestion - I’m sure were I omniscient I could come up with a much better way.
It may take a very long time - if certainly shorter than eternity - but I believe that eventually he would see the error of his actions and beliefs. Then he would be allowed into heaven.
I don’t believe that a just, merciful, god could allow it any other way. (Then again, I don’t believe really believe in a god at all).