Forgive Everyone Everything

Unforgiveness/bitterness/resentment/holding grudges is a hindrance to our prayers and our intimate relationship with God. If you don't forgive, you disobey God. God wants us to forgive anyone anything. Treat others with agape love, grace, kindness, and compassion. If we want our prayers to be answered, our hearts must be right with God, and that includes having a right attitude towards people. This alone should be enough motive to forgive :). "If I had cherished sin in my heart, the Lord would not have listened; but God has surely listened and has heard my prayer." (Psalm 66:18-19) Yes, unforgiveness is sin!

By the way, in this verse, Jesus is not referring to God's forgiveness (that comes with our salvation and reconciliation) which we receive when we repent and believe in Jesus Christ and His finished redemptive work on the cross. The penalty for our sin is fully paid by Christ and we are fully forgiven by grace alone through faith in Christ alone. Our eternal destiny does not depend on our forgiving others. Here Jesus is referring to our day-to-day prayer of confession, asking God to forgive us our sins (1 John 1:9). Our sweet fellowship with our Heavenly Father is interrupted by sin (including the sin of unforgiveness).

"The person who is living by grace sees this vast contrast between his own sins against God and the offenses of others against him. He forgives others because he himself has been so graciously forgiven. He realizes that, by receiving God's forgiveness through Christ, he has forfeited the right to be offended when others hurt him." (Jerry Bridges)