It's the unforgivable sin, according to the gospel reading from Mark last Sunday.
I remember reading the gospel at the early service last Sunday, out on the lawn, and when I got to this part, I saw one man near the front row, raise his eyebrows. I'm not sure if he raised his eyebrows at the part about "blaspheming the Holy Spirit", or about "the unforgivable sin", or if it was a combination of the two, but my immediate thought was, "I should have preached about this. People are going to wonder about it."
Preachers, does this ever happen to you? You think you have listened to the Holy Spirit during the week, and as you are reading the gospel, or one of the readings, or as you begin your sermon, you look out at a particular face, and sometimes you even know a story about what that person is struggling with, and you think, I should have preached on this.
I remember thinking about it when I was preparing the week before. There was plenty to wrestle with in the story, plenty to think about, from "family values" to "a house divided," and of course, "blaspheming the Holy Spirit." Back during my dalliance with the Pentecostals, this was one of the verses they liked to talk about, since it highlighted the importance of the Holy Spirit. You can even say bad things about Jesus, and he'll forgive you -- but don't say anything bad about the Holy Spirit! That's what my Pentecostal friends said. So there was a lot of speculation about what "blaspheming the Holy Spirit" would actually look like.
Actually, though, as a Lutheran, it's the "unforgivable" part that gets me. How can there be an unforgivable sin? Confession and absolution is a non-negotiable part of the liturgy for me. And you notice that we always say, "In the name of Jesus, I forgive you some of your sins"? Oh, you notice that we don't say that? We say ALL of your sins. Because we believe that words have power, and that the Word has power, and that when I say "your sins are forgiven," Jesus has bound the strong man and thrown him out.
You know what I think the blasphemy against the Holy Spirit is?
It is to believe that there is any sin that God can't forgive.