I think that for believers, unforgiveness is the greatest cause of affliction. That ought not be the case.
Scriptures plain on this subject: “but if you do not forgive others then your Father will not forgive your transgressions.” Matthew 6:15.
God in His mercy created the human body such that it is unable to live well in that environment. We must heed its signs.
Things like anxiety, regret, anger, hatred, unforgiveness, and jealousy are known killers. They eat away at our immune system and set us up for all kinds of physical calamities.
~ Bill Johnson