There can be a person who draws the line at forgiving a certain person. There may be someone they have decided they are not going to forgive. They may feel that, if God is going to require them to forgive that person, then they are not willing to be a Christian. This may be the place where they become the person described in Hebrews 6:4-6. Up to this point they may have demonstrated all the wants and desires of a new or untrained Christian; but, once they come to this point in Christianity, they decide Christianity is not for them.

Forgiveness is not negotiable with God.

Mat 6:14-15 (NIV) 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.

As long as a person is WILLING to keep seeking God for a forgiving heart for each person they haven’t YET forgiven, their lack of forgiveness is credited as forgiveness in their record. But, God knows the difference between the person who is ACTING like they want a forgiving heart and the person who REALLY wants to forgive but isn’t yet able (Romans 7:19). The true Christian HATES their lack of forgiveness and wants to be set free (Romans 7:15).