That's a great question Jon. The question touches on a lot of high level doctrinal issues, so I'll call them out without delving into them much.
I can only answer in accordance with my own theological framework. I'm a Calvinist (that's not a denomination but a belief set that arises from reading the Bible in a certain way) so this question isn't particularly difficult. I have no idea how a classic Armenian handles it, I suppose for a true Armenian, since you can lose your salvation anyway (without blaspheming the holy spirit), the answer is pretty clear. I also have no idea how a Catholic would answer it, so I can't speak for them.
Warning, this post may contain theology that may or may not be something you want to read on a jiu jitsu forum. If you don't like it, don't read it. You have been warned!
1) Perseverence of the Saints (this is a core tenant of Calvinisim that is so awesome even some Armenians like it): if you're saved, you're saved. Done. Part of the idea here is that saved people are
changed people.
Our faith is not a list of crap you should do and not do to be saved and your sins get weighed against your good acts to determine where you go. If your sins are forgiven then your sins are forgiven, period. And then you are given the capability of living a changed life that you didn't have beforehand.
2) Total Depravity of Man:
everybody is a total piece of garbage, some people just do a really good job of pretending they aren't. Jesus wasn't down with that crew and ultimately got murdered by them. So you are right that nobody is beyond redemption according to our faith. But people are too broken to choose God, our situation is such that our depravity causes us to reject him.
3) Unconditional Election / Irresistable Grace : Since you're too broken to choose him, God chooses you and saves you having nothing to do with how awesome you are, how good looking you are, what kind of good works you've done or any other thing that might cause a human being to choose or admire you. Depending on how you see this, you might say "You really don't get a choice in the matter." My view (based in scripture) is that you are enabled to make the obvious choice of not rejecting God in a way that was previously impossible for you. It may seem like splitting hairs, but from my perspective, the difference is huge. We can argue about the free will implications later.
Now we get to a sin that as far as we can tell was committed once in the entire history of humankind. Jesus, God Incarnate is walking around doing good deeds through the power of the Holy Spirit. And some Pharisees (these guys are, in a nutshell, self appointed religious enforcers / do gooders / holier than thous and have added a bunch of rules to the ones God gave people to keep people extra super duper safe) don't like it. They accuse him of working through the power of Satan. And, funny thing, God doesn't like being accused of that, that's some pretty high level blasphemy. This is where the idea of blasphemy of the holy spirit comes from and it is here that Jesus says "blasphemy of the holy spirit will not be forgiven." Now, there are some questions of whether this sin can even be committed today since Jesus isn't hanging out on earth anymore. I'll leave that alone, just keep it in mind. It appears that the sin is at some level "attributing the work of God to Satan."
Now it's time for some systematic theology.
The goal here is to determine how all of this can be true at the same time without damaging your interpretation of other bits of text.
And it isn't very hard in this case.
For the Calvinist, the Perseverence of the Saints doctrine gives us a framework to understand this in. That would suggest that a Christian would be prevented from committing this sin (if indeed it can still be committed). The unconditional election doctrine tends to point towards 1) This sin is impossible to commit today or 2) God has somehow prevented anyone who is elect from committing it before they are saved. The latter may be hard to believe, but the idea that "if you walk in the Spirit you will not satisfy the evil desires of the flesh" is very scriptural.
So that's it. It's possible that this sin is no longer a factor because you can't really walk up to Jesus and call him a satanist or a sorceror. If it is possible to commit, it's still not a factor. Bottom line: according to our beliefs,
you can't choose God anyway and God isn't prevented from choosing you.