I learned a long time ago that some people would rather die than forgive. It's a strange truth but forgiveness is a painful and difficult process. It's not something that happens overnight. It's an evolution of the heart.
The principle that certain sins should not receive the Church's testimony of forgiveness was probably no novelty at all but had been applied in various churches perhaps however with no strict consistency.
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One can't relive one's life. Forgiveness is not what's difficult one's always too ready to forgive. And it does no good that's obvious.