Human beings have a combination of goodness and evil proclivities in them. External stimuli and environment elicit certain kind of reactions. Without fear of punishment, we would give free rein to our evil inclinations. Law-enforcing authorities exist to mete out punishment and keep our evil tendencies in check. When law-enforcing authorities and the government condone evil, rather than strongly condemning it and ensuring punishment for the guilty, human beings take it as a licence to indulge in their deepest evil desires.
Death penalty for child rapists is a good idea. If enforced and executed properly (without falsely implicating innocent people), it should act as a deterrent to human beings in general from committing such crimes. This law applies to other crimes as well.
