Forgiveness is your letting go of things that upset you. It is not a requirement not even for a Christian man like yourself. I'm sure others who know their scripture better than a skeptic like me can dig into this more.
Matthew 6:14-16
For if you forgive men when they sin against you, your heavenly Father will also forgive you. But if you do not forgive men their sins, your Father will not forgive your sins. (NIV)
Luke 6:37 Do not judge, and you will not be judged. Do not condemn, and you will not be condemned. Forgive, and you will be forgiven.
Just two of many verses in scripture regarding forgiveness. It's not always easy and maybe not possible right away, but it's clear that it is expected of Christians. It's also a frequent topic of Christian sermons.
