Since when does being Christian mean one doesn't believe criminals should serve their sentences?
I was not born a Christian, but from everything I have heard, if someone repents for their sins, they are forgiven by Jesus Christ, the Lord. May be those murderers in AR repented, and pastor Huckabee felt it was his Christian duty to pardon them.
That is now how my Hindu religion works. Every good deed and every sin you commit determines what kind of life you will get after re-incarnation. Sins are never forgiven. You have to pay for them by doing enough good deeds to have chance at a better life during next life.