Truly I tell you, people can be forgiven all their sins and every slander they utter, but whoever blasphemes against the Holy Spirit will never be forgiven; they are guilty of an eternal sin (Mark 3:28-29).
An eternal sin? Never forgiven?
That’s a show stopper! Matthew and Luke also mention this warning. Even John mentions a “sin that leads to death” (1 John 5:16).
But what is it?
Context, and a little Old Testament, can help our understanding. In Numbers 15:27-31 God speaks of sin that “remains.” Unforgivable, it is the defiant sin. The prophet Eli’s sons persisting impenitently in what they knew God found reprehensible. Eli himself committed it because he refused to discipline his boys. They became “un-atoneable.”
Most sin takes us on a steady, slight, spiritual decline. The problem with defiant sin is that the slope is at a greater angle and before we know it, we’re at a dead run in the wrong direction we cannot stop.
In our text, Jesus’ opponents are distressed by teaching they perceive as “new” and at odds with what they’ve always thought. Rather than carefully consider who Jesus might be (and the truthfulness of his words) they sought to counter the Lord with a “name calling” campaign to impugn his reputation. While Jesus is willing to forgive them, he knows they are unwilling to repent and will later even oppose His replacement, the Holy Spirit. They are racing down Fool’s Hill to the city of Beyond Hope.
All sins, really, are forgivable – as long as we turn from them. The eternal sin begins as one we won’t turn from. It ends as one we can’t turn from. That’s what makes it eternal. Consider the road you take. It may not have an exit.