31 Let all bitterness, wrath, anger, clamor, and evil speaking be put away from you, with all malice. 32 And be kind to one another, tenderhearted, forgiving one another, even as God in Christ forgave you. (Ephesians 4:31–32, NKJV)
Bitterness is like acid eating through one’s heart. There is no room for compassion, kindness and merciful forgiveness in the bitter heart. The companions of bitterness are angry, resentful responses, evil words and ill will. Christians must put away all these things from their hearts. This can be done by recalling the kindness of God toward us in Christ. God could have been bitter toward us because of our sins against Him. But, His kind love forgives us in Jesus. There can be no room in our hearts for bitter resentment. Be kind. Be merciful. Forgive. That’s how God has treated you in His Son, Jesus Christ.