People will say and do things out of rage and anger... I believe God forgives what ever the cause, if I were God, I know I'd send murderers/rapists straight to hell! But like everything I believe God gives us chances to redeem ourselves; if it be a next life or a different level/dimension. Speaking ill of the Lord, I've done it I will say, but I never ment it.. I think only a mentally insane being would mean something like that.
Everything can be forgiven, but I don't believe it will be forgotten.
The unforgivable sin then, is the sin of refusing Gods demand that a man repent and be saved.
Since the Bible is the source of the idea of a sin that God will not forgive (unforgivable per Jesus and Paul), then perhaps you should provide Biblical evidence for your conclusion that blasphemy of the Holy Spirit is the same thing as refusal to become "saved".
How little we understand God. To me the Holy Ghost is the telepathic connection that God establishes with all of us at conception. Cursing the Holy Spirit is therefore cursing God. If we follow our God given natures and see all the evil in the world, it is natural to feel anger. Anger must be vented from our psyche if we are to be healthy. Since God created all then He should be the recipient of this anger. In a perfect world like ours cursing God is useless unless we are arguing for a change in the number of evil in the world. All we can argue with Him about is the percentages of evil and good.
These percentages are fixed by God in the beginning. All our cursing then is really a prayer for the end time when these percentages are looked at and hopefully revised or explained to us to ease our minds. The numbers is truly what we curse and are not only allowed but praiseworthy.
God made us all perfect, only good can come from us. The fact that evil is here is only so that we can recognize it and we do.