But if you do not forgive others their sins, your Father will not forgive your sins. Matthew 6.15
At first glance, these words of Jesus might seem threatening, childish even: tit for tat. But that would be to miss the point: an unforgiving spirit cannot receive forgiveness. The inability, or unwillingness, to forgive has been likened to a rusty nail, which lodges in the body and spreads infection, eventually killing the host.
Ridding the body of such an unwelcome guest is not pleasant. Nor is purging the soul of an unforgiving spirit an easy process. Both are necessary for the flourishing of the whole person. Jesus came to do the hard work, by setting us free from sin and death by becoming our sin and being nailed to the cross as the "perfect sacrifice". His resurrection confirms the success of his mission and the implication for us is that we can recover from the poison of all sin, including an unforgiving spirit, by accepting Jesus as Saviour and Lord. Furthermore, the cure is for this life and forever.
That might sound too good to be true. But can we afford to reject such an invitation? Only if there is a better alternative - and there isn't!