How can I forgive?

As believers we're taught to Forgive, but isn't there a limit to what we can forgive?

Do we "forgive and forget" ... as though nothing ever happened? Isn't forgiveness meant to be unconditional? But then if we forgive a child molester, does that mean we must allow that person to baby-sit our kids ... as if we've forgotten what happened?

What does forgiveness mean, really?

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To forgive means:
- to grant pardon for
- to renounce anger or resentment against
- to not seek retribution or retaliation
- to absolve from payment

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When Jesus had received the sour wine, He said, "It is finished!"* Then bowing His head, He gave up His spirit.
- John 19:30

*Greek tetelestai - "paid in full"