Unforgiveness isn’t just a bad feeling; it’s a serious spiritual state, often hardening your heart so completely against God’s mercy that you refuse to be forgiven, a state of final impenitence where one chooses sin over God. While unforgiveness itself isn’t the only unforgivable sin, clinging to it, resisting God’s grace, and refusing to pass on the forgiveness God gives you (as taught in the Lord’s Prayer) creates a spiritual block, cutting you off from grace and leading to inner torment like fear and depression.