W. Austin Gardner
God Condemns an Unforgiving Spirit

Why do you suppose God so hates an unforgiving spirit? There are three reasons.
1. It shows an indifference to the greatest thing God did.
2. We interrupt God’s purpose in the world: reconciliation.
3. God hates ingratitude.
R. T. Kendall, Total Forgiveness: When Everything in You Wants to Hold a Grudge, Point a Finger, and Remember the Pain - God Wants You to Lay It All aside (Lake Mary, FL: Charisma House, 2010).