Jesus taught us to pray, “And forgive us our debts, as we forgive our debtors” (Matthew 6:12). This part of the Lord’s prayer is first a gospel prayer and then a gracious prayer.
Jesus did not teach us to pray, “Forgive us our debts, because we forgive our debtors.” That would make God’s forgiveness of our sins dependent on us forgiving others. Instead, the preposition “as” suggests that our willingness to forgive others is evidence that God has forgiven us. In other words, forgiven people forgive people.
An unforgiving spirit is inconsistent with the kingdom of God and might be an indication that you don’t know God. However, forgiveness is a gracious act of the will that flows from people who have been forgiven much.