He also has written a book, "Forgive for Love," about relationships. He said that without forgiveness, damage is often passed on, sometimes from generation to generation.
"And that's that fulcrum point where this whole world kind of totters," he said. "You did it to me. Therefore, I can do it back."
Anthropologist Helen Fisher said forgiveness has been essential "from a Darwinian evolutionary perspective."
For instance, it is a part of chimpanzee culture.
"Males have battles every day for status and there's always a winner and a loser," Fisher said. "Forty percent of the time within the next half hour, they reconcile. They forgive each other. They will put their hand out to each other in a gesture of reconciliation. They'll come over and kiss each other on the lips. They'll pat each other on the back."
Luskin conceded that people who are too quick to forgive risk becoming doormats.
"Forgiveness is not the same as getting a lobotomy," he said. "You still have to think and take care of things and act with intelligence and discrimination."
Psychiatrist Thomas Szasz, in a famous quote, put it this way: "The stupid neither forgive nor forget; the naïve forgive and forget; the wise forgive but do not forget."
There also was a significant difference between Porter and those who could not forgive Cutts. Porter had taken responsibility for Blake, the son that Cutts had fathered with her daughter.
"I serve an amazing God, Bobby, a God that forgives," Porter said at Cutts' sentencing hearing. "And I made up my mind that I would forgive you. … I would have never been able to raise Blake and hate you."
She asked the judge to consider a sentence that would someday allow Cutts to leave prison and hold his son.
"And I hope and pray that I'm able to raise [Blake] to forgive you," she told Cutts. "He knows what you did."
There was a sign of emotion from the 30-year-old Cutts -- a tear -- shortly after Porter finished her statement. He showed no emotion when he was sentenced to life in prison with the possibility of parole only after he has served 57 years.
"I didn't think I could raise my grandson to be any kind of a man if I was full of hate and anger," Porter said later. "My daughter would have never wanted that either."
"My forgiving [Cutts] didn't change anything as far as what was going to happen to him," she added. "But it changed me. It's almost like it gave me the freedom to mourn my daughter's loss and not feel that awful rage that happens to you when you choose not to forgive people. I was not going to let this destroy me as well."
Visit http://www.blakesbrighttomorrow.com/ to find out about a college fund for Davis' son, Blake.