The Unpardonable Sin

We are in Mark iii in our Tuesday night Bible Study/Fellowship. This coming Tuesday will undoubtedly be submerged in and by the discussion of blasphemy against the Holy Spirit and the Unpardonable Sin. I've been trying to do an early study. What I would like to do is present to the group the many different interpretations that exist right now. I am also gathering certain quesitons that could be asked about the subject, particularly with respect to the text of Mark iii.

So far I have seen quite a few commentaries or study notes talk about the unpardonable sin being very specific to the situations explained in the Gospels and how this sin cannot be committed today.

I have also heard it taught that this unforgiveable sin is basically the rejection of Christ, the rejection of God.

I don't know if either of those two explanations work for me. Why? On the first one, the language of Mk. iii, Mt. xii and Lk. xii seem general in the way Jesus refers to those who commit the sin. If blaspheming the Holy Spirit can be done, than anyone can do it, right? Well, yes, anyone who has not been regenerated by the Spirit and is still in sin can surely blaspheme God. On the second one, that idea seems too general. In Mk. iii.29-30 we find this written:

but whoever blasphemes against the Holy Spirit never has forgiveness, but is guilty of an eternal sin"--[and Jesus said this] for they had said, "He has an unclean spirit."

That seems specific. They claimed He was an agent of Satan, so He told them any who blaspheme against the Holy Spirit will not be forgiven. Seems like a 1:1 correspondence.

But, that's why we study. I have put together some questions to ask, and maybe I will have the opportunity to ask one or two. They are real simple (and again this is preliminary):

1. What is the unpardonable sin?
2. What does "unpardonable" mean? Does it mean that it is outside of the salvific efforts of Christ? Is this "sin" incapable of being covered by Christ atonement? Is it the choice of God not to forgive this particular sin, while forgiving the rest?
3. Who can commit the unpardonable sin?

I've read a couple of places that if you are wondering if you have committed the unpardonable sin then you haven't. That's so simple and profound at the same time.