I see it as a false choice.
First I will quote from The Meditations By Marcus Aurelius (Roman emperor 26 April 121 - 17 March 180)
"The best way of avenging thyself is not to become like the wrong doer"
http://classics.mit.edu/Antoninus/meditations.6.six.htmlForgiveness is not necessary, there is no reason not to seek justice...However, make sure your motives are out of seeking justice solely for the sake of protecting those who would be harmed by such crimes, and not revenge, else you harm yourself as well. Temper that justice with mercy, if the person understands their crime and asks for it.
Mercy does not mean you forgive...or "turn the other cheek"...
Turning the other cheek is a noble gesture, if...IF it is to turn the heart of the person who stuck it. However, if dealing with a sociopath or something of that nature, You will find yourself with two bruised cheeks, and nothing more.
Also, Punishment should only be to protect the society, not for revenge, and the punishment needs to be only what is necessary to accomplish that objective.
The Eye for an Eye only makes two monsters.
On a similar note, a major reason I never believed in hell, is because it is a punishment with no reason...when asked "What about Hitler...or some other evil person blah blah" I respond "Why keep evil alive...even if just to punish? It makes no sense, you are simply punishing evil with evil, therefor creating more evil..".