How do I overcome a bitter spirit?

On the human front, the biblical strategy for overcoming bitterness is forgiveness. Forgiveness is making a commitment to release the offender from the punishment you believe they deserve for the hurt they’ve caused. Often the bitter person will insist that the offender doesn’t deserve forgiveness. This places the angry person in the judge’s seat and only further fuels his bitterness. The Bible, however, doesn’t teach that you forgive your offender because they deserve it. Instead, it teaches that you forgive someone because you were yourself forgiven by God when you deserved it least. In the verse immediately following our passage of study we read, “Be kind to one another, tenderhearted, forgiving one another, even as God in Christ has forgiven you [emphasis added].

Taken from Fighting the Fire: biblical strategies for overcoming anger, p. 11