You should not hold bitterness within you. Bitterness is a poison. It takes away the joy of the Lord from you. You should not harbour resentment against anyone, be it a Christian or not. No matter how callous anyone acts towards you, do not hold grudge, bitterness or revengeful thoughts.
You are to live a forgiving life. When others hurt you, forgive them without delay or second thoughts. When you do this, you will have a happy life and find joy in others.
You are to practise God’s word. Get rid of all bitterness, rage and anger. Express God’s love to others by living a love filled life.