Forgiveness and Justice - Why So Hard To Understand?

Somebody wrongs us - we are expected to forgive them. If it is a crime - then it is the God-appointed function of society to punish them. We are all answerable to God and Society. If someone burgles your home - it is your duty to society to report it. It is your duty to God to forgive.
For centuries, Christians have known these things. Why has all this changed in the last two generations?