When Jesus made it so very clear that our forgiveness is, to some extent at least, conditional on our being forgiving, we should all grasp how vitally important this is.If this is hindering your spiritual life - then maybe, just maybe, I can help a little.
1) Bitterness is a negative which damages us. Nonetheless, do not worry too much about your feelings where institutions are concerned. It is better not to hate if at all possible but I would not get too 'hung up' on your feelings towards the Inland Revenue, for example, which appears to have robbed you. (It could never accept your forgiveness, in any case.)
2) Ignore people who tell you that you must 'forgive AND forget', thus implying that you have to trust somebody who is clearly untrustworthy. This is nonsense.
If somebody has punched you on the nose - you forgive but DO NOT fail to walk past them very carefully in the future. If there is a Scripture that tells us that we have to trust under such circumstances - then I have no idea where it may be found!
3) Do remember that you cannot forgive on behalf of other people.
4) When you really cannot forgive, perhaps because the wrong is so enormous, try this:
Ask yourself if you would forgive if that person came and asked you for forgiveness. (If you would refuse at this point - you do have real problems.)
The answer should be a resounding "yes" and you are well on the way back to spiritual health - but do ensure that any negative feelings are not allowed to resurface.
Take these steps and I am certain that God will help you to go the rest of the way.
Imperfect though this advice may be - if it helps just a little - I would be delighted.
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