This is not un-Christian. Christ Himself said that for anyone that harms one of the little ones, it would be better if a millstone were tied around his neck and he was thrown into the sea.
So, you are advocating a lesser punishment than Christ has in mind for them.
You're so right! How have we forgotten this? There should be no sympathy or understanding for anyone who commits a crime against a child. And they should never, ever be released after even one offense. There should be no forgiveness for this type of crime.