"Since the NT makes it clear that God is willing to forgive any sin we are willing to confess, the "worst" sin would have to be a sin that would prevent us from ever wanting to repent of it. I take this to be the "sin against the Holy Spirit," or "the unforgivable sin."...Icon is right in pointing out that this is precisely what the Pharisees did with Jesus (Mt 12). But Jesus then WARNS THEM about a sin that is unforgivable. He doesn't conclude that they HAD in fact committed this sin, but given the depth of their blindness (to confuse metaphors) they called a work of God a work of Satan! It seems Jesus is worried that they have irrevocably resisted the Holy Spirit.
I stick with the worst sin being resisting the Holy Spirit so thoroughly, so repeatedly, that one has ensured that they will never WANT to do otherwise. NOW their doing of sin has become a BEING of sin."
Vexen's reply and agreement: (posted on 2002 Jan 16 to Boyd's msg board at Christus Victor Ministries)
From an ultimate Christian perspective this seems to be one's ultimate undoing, to take yourself to a point where even at death you reject God.
I witnessed this in some people, for example some people have said "even if I did believe in souls, I don't think I have one"... this spiritually-denying attitude I have called "deadism", a person who is a "deadite" will fervently reject the Holy spirit over a long period of time.
This deadism concept seems to match Boyd's definition of the unforgivable sin. It seems to me, though, that this would be forgivable if the individual repented and came round. The "unforgivable" aspect is that the person does not wish to be forgiven (which also superficially sounds like Pride, again), but the source is more in stubbornness and habitual disbelief, a deep feeling of God (in the form of the Holy Spirit) not being present.
It is obvious that such deadites are hardened (of heart) more and more when they are evangelized by Christians, causing deeper resentment and longer-term intense rejection of Christianity.
Deadism is atheism's equivalent of closed minded fundamentalism, adherents (or victims?) of both are unable to change their minds, it feels and seems beyond their control, a self reinforced mode of being. I do not know that once people are in such a state they can change their mind, so perhaps this is how it can be "unforgivable". It is unforgivable to let yourself go down a path that leads to an inability to accept change or new things.
"Vexen is a deadite. We believe that if Heaven exists, we cannot go there. We believe that if Satan and God will commandeer armies in the Biblical wars of Revelations, that we are to fight on the losing side of Satan. We believe that our time will come, that there is no afterlife for us no matter which theology you consider true""Deadism: Unholy mankind" by Vexen Crabtree, 2002 Jan 06
Criticism of Greg Boyd's idea of what unforgivable sin is:
The problem is with my "deadism" or Greg Boyd's definition of unforgivable sin and how you can blaspheme "permanently" against HS, is that they're both so wishy-washy long term, and stick of modern abstraction and convolution, whereas I do not find that any other ideas of sin and blasphemy in the bible are anywhere near as unclear - it smells like we're adding layers of interpretation and complication in order to make it make sense, rather than actually understanding what was meant.
If I was an early messianic Jew or roman who believed in a more OT-style god who could punish forever, then, I wouldn't actually tell anyone what the unforgivable sin was, so that no-one would go do it intentionally in order to get rid of those pesky Christian evangelists from trying to convert them!
"Get lost Christian, pester someone else, I've committed the unforgivable sin!"
By Vexen Crabtree 2002 Jan 16