From that time on, Esau hated Jacob because their father had given Jacob the blessing. And Esau began to scheme: “I will soon be mourning my father’s death. Then I will kill my brother, Jacob.†     Genesis 27:41 (NLT, my emphasis)
Bitterness became Esau’s life. He held a grudge. He was bitter about what Jacob had done. Was Jacob wrong? Absolutely! And while Jacob’s actions would cause him to be exiled from his family and live a life of fear, constantly looking over his shoulder, Esau, too, was condemning himself to a life of fear with the holding on of this bitterness. Esau was ‘afraid’ that Jacob would not get what he deserved.
Bitterness against someone for what they have done to me and fear that they will not receive their comeuppance is the root of nothing less than vengeance. Bitterness will cause me to miss God’s grace and the joy that life can give.
Work at living in peace with everyone, and work at living a holy life, for those who are not holy will not see the Lord. Look after each other so that none of you fails to receive the grace of God. Watch out that no poisonous root of bitterness grows up to trouble you, corrupting many. Hebrews 12:14-15 (NLT, my emphasis)
Bitterness is not an amoeba. It is not a forever one-cell ‘animal’ in my heart. It grows. It reproduces itself and destroys everything that it comes into contact. It truly is a cancer in my spirit! Bitterness will manifest from inside of me when I lose my temper. It will cause high blood pressure, irritability, sleeplessness, depression, a constant negative perspective, and inability to find joy even in praise and worship of my Lord.
How do I get rid of bitterness? With forgiveness. No matter what the offense, with God’s help, with the power of His Holy Spirit, I can extend forgiveness to the offender and release that person. Reconciliation is not an essential component of the forgiveness. But letting go of unforgiveness and bitterness is.
How can I be sure that bitterness and unforgiveness are gone in my heart?  R.T. Kendall said in his book, Total Forgiveness, “Bitterness is gone when there is no desire to get even or punish the offender, when I do or say nothing that would hurt their reputation or future, and when I truly wish them well in all they seek to do.â€
I believe that my inability to release forgiveness toward someone and squelch bitterness forever comes back to anger with God. Now there is a hard lump to swallow! When terrible things happen in my life, it is hard for me to believe that my all-knowing, all-loving God allowed them to happen. Where is Your plan in that, God?
I would be foolish to say that I know the complete answer to that question. In allowing Lazarus to die, Jesus said He was glad He wasn’t there to prevent the death “so that you may believe†(John 11:15). If I knew the where and why of suffering and evil, I would not have to have faith in God, would I? Romans 8:28 tells me that “all things work together for good for those who love Godâ€. Jesus came not to explain the evil in this world but to live a Spirit-led life despite the evil. He came to show me graciousness, forgiveness, mercy, and agape love from the lowliness of a manger to the horrific pain of the Cross. He deserved better. Duh! And yet, He showed me what forgiveness and a heart without bitterness was all about.
He was despised and rejected—a man of sorrows, acquainted with deepest grief.
We turned our backs on him and looked the other way.
He was despised, and we did not care…
But it was the Lord’s good plan to crush him and cause him grief.
Yet when his life is made an offering for sin, he will have many descendants.
He will enjoy a long life, and the Lord’s good plan will prosper in his hands.
When he sees all that is accomplished by his anguish, he will be satisfied.
And because of his experience, my righteous servant will make it possible for many to be counted righteous, for he will bear all their sins.
I will give him the honors of a victorious soldier, because he exposed himself to death.
He was counted among the rebels.
He bore the sins of many and interceded for rebels. Â Â Â Isaiah 53:3, 10-12 (NLT, my emphasis)
If there is someone that you need to forgive, do it! Take time and ask God to help you to do it. God will help you. All you have to do is ask. I tell you the truth (from my own experience), unforgiveness will slowly destroy you. Forgiveness will heal you and set you free. Indeed.