In all my years of teaching Scripture and attempting to disciple new believers, I can usually count the minutes until this question comes up. Most new Christians, especially if they came from a church background, are worried about this. For some reason, this has caused more consternation among God’s children than just about any other problem, and so many people are wondering and worrying whether they’ve committed this “unpardonable sin.” Let’s take a look at this passage and some others so that we can think clearly and biblically about this.
So the crowds are around Jesus, and his family actually comes to take him away as a crazy person. His own family, the ones with whom he had grown up, were coming to seize him as someone who’s mentally unbalanced. Of course, his own (half-)brothers didn’t believe in him, but this is a bit much. It just goes to show that neutrality concerning Christ is not a long-term option. You’ll either dismiss him and try to lock him up as a madman or bow at his feet as Lord.
And what was the Pharisees’ reaction to him? They saw his miracles, heard his teaching, saw the changes in peoples’ lives, and called him demon-possessed. This is where the really controversial subject comes up. And if all we had of God’s word was Mark’s Gospel, we’d really be confused. Thankfully this isn’t the sum total of what we have. So let’s use the rest of Scripture and some sanctified common-sense to sort this out, shall we?
First, notice first that Jesus seems to make a strong distinction 1) between “sins and. . . slander" that people commit everyday and 2) “[blaspheming] against the Holy Spirit.” Matthew’s version expands on this a little bit, making a contrast between 1) “[speaking] a word against [Jesus] and 2) [speaking] against the Holy Spirit.” So there’s something different about this one sin that sets it apart from others.
And one obvious thing that sets it apart is the very possibility of being forgiven. Jesus doesn't say "If you commit this sin, you're in real trouble unless you repent and ask forgiveness." No, he says that anyone committing this one sin will never be pardoned, in this life or in the one to come. Let me remind you, we’ll see murderers in heaven (like David), so whatever this “unpardonable” sin is, it’s not murder. Same with adultery. Same with theft. Also let me point you—once again—to 1 John 1:9, which promises that if we confess, he will forgive and cleanse. The passage in Mark is talking about an offence which, once committed, will never be forgiven. Not ever.
And why would Jesus make it a point of mentioning the Holy Spirit? Why is offending the Holy Spirit so serious that you’ll never be forgiven? As opposed to offending Jesus, which I do with every sin?
Again, the key is knowing your Bible. In John 16:7-11, we’re told that it’s the Spirit’s job to convict the world of sin, righteousness, and judgment. And not just any old sin. In this passage the Spirit specifically convicts us of not believing in Jesus. Yes, that’s a sin. In fact, I would submit that it’s the only sin that God won’t (and can’t) forgive. What's the “unpardonable” sin? How can you “blaspheme against the Holy Spirit”? Well, it’s the one sin that’ll keep you out of heaven, namely rejecting Jesus as Savior. And it’s the Spirit who’s telling you that you need to submit to Christ and trust him.
That’s why vs. 30 actually tells us what the Pharisees had done which was so bad. By claiming that he was demon-possessed, they'd done much more than just slandering an innocent man. By looking at his miracles and by hearing his teaching and yet still accusing him of working with Satan, they were showing that they were utterly closing themselves off to their only hope.
So if you’re worried about committing this “unpardonable” sin, stop. If you had committed it, you wouldn’t be worried about it. But let’s focus on the positive side of this for a moment, shall we? Each one of us who's trusted in Christ can personally testify that all types of sins and blasphemies are forgiven. His blood has covered our sin once and for all, and it will never be brought up again. Kinda makes your day, doesn’t it?
Lord Jesus, I know what it cost you to forgive me. May I never forget, may I never get over it. Never.