I’m preaching this Sunday on Mark 3:20-35, which includes Jesus’ sobering warning in vv. 28-29, “I assure you that human beings will be forgiven for everything, for all sins and insults of every kind. But whoever insults the Holy Spirit will never be forgiven. That person is guilty of a sin with consequences that last forever” (CEB). Jesus is referring to the so-called unforgivable sin, the threat of which often troubles the consciences of Christians. “After all,” one might think, “what if I’ve committed it without even knowing it?”
My short answer is that if you’re worried about having committed it, you haven’t. In his commentary on Mark’s gospel, David Garland agrees:
If one understands the so-called unforgivable sin as deliberately scorning the power and forgiveness of God, one can perhaps help those in the church who become worried, or even terror-stricken, that they have committed some sin that is unpardonable. That they even worry about it provides proof that they have not committed such a sin. Jesus affirms that blasphemy is forgivable (3:28), and the testimony of Paul confirms it. He identifies himself as a former blasphemer (1 Tim. 1:13), one who was no different from these teachers of the law in rejecting Jesus and maligning Christians as a satanic cancer destroying the fabric of Judaism (Gal. 1:13-14). He came to a new understanding through the direct intervention of God. It would have been unforgivable had he continued to spurn the Lord, not because he had squandered his one opportunity to respond, but because his heart would have grown more calcified and harder to penetrate and his ways more settled in iniquity.[†]
† David E. Garland, Mark: The NIV Application Commentary (Grand Rapids: Zondervan, 1996), 136.