This is a very common question Christians ask their pastors after they commit what they think are serious or heinous sins, such as murder or adultery. We know from Scriptures that King David was forgiven by God of these two sins.
Jesus speaks of this blasphemy as the “unforgivable sin.” This is a most serious question, one that often causes a Christian sleepless nights and nightmares. Three parallel passages in the New Testament concerning this subject are:
• Matthew 12:31-32: Therefore I tell you, every sin and blasphemy will be forgiven people, but the blasphemy against the Spirit will not be forgiven. And whoever speaks a word against the Son of Man will be forgiven, but whoever speaks against the Holy Spirit will not be forgiven, either in this age or in the age to come.
• Mark 3:28-30: Truly, I say to you, all sins will be forgiven the children of man, and whatever blasphemies they utter, but whoever blasphemes against the Holy Spirit never has forgiveness, but is guilty of an eternal sin”—for they were saying, “He has an unclean spirit.”
• Luke 12:10: And everyone who speaks a word against the Son of Man will be forgiven, but the one who blasphemes against the Holy Spirit will not be forgiven.
Many interpretations have been offered about these passages. John Calvin, for instance, disagrees with Augustine’s view that “it is obstinate perverseness, with distrust of pardon, continued till death” because it “scarcely agrees with the words of Christ, that it shall not be forgiven in this world.”
Calvin’s own interpretation is that the one who commits this sin is one “who, while so constrained by the power of divine truth that he cannot plead ignorance, yet deliberately resists, and that merely for the sake of resisting.” What Calvin then says is that one who knows the true gospel but willing resists it cannot be forgiven. It is the sin of unbelief. So he concludes, “The spirit of blasphemy, therefore, is, when a man audaciously, and of set purpose, rushes forth to insult his divine name… If ignorance joined with unbelief made him obtain pardon, it follows, that there is no room for pardon when knowledge is added to unbelief” (Institutes of the Christian Religion, III.iii.21, 22).
And this view is very similar to John Piper’s view, when he says, “The only unforgivable sin is the sin that we refuse to confess and forsake. We commit unforgivable sin when we cleave to a sin so long and so tenaciously that we can no longer confess it as sin and turn from it. [It] is the resistance against the Holy Spirit’s convicting work to the point where he withdraws, leaving the sinner in helpless hardness of heart, unable to repent” (What Jesus Demands From The World, 320). This is what is commonly called “hardening of the heart” when “God gave them up in the lusts of their hearts to impurity” (Rom 1:24, 26, 28; cf Acts 7:51). In the case of those who have participated in a true church, but later have apostatized, rejected Christ, fallen away, they will not be restored again to repentance (Heb 6:4-6).
But the context of the three Gospel passages is different altogether. In the Matthew and Mark passages, Jesus says these words to Pharisees and scribes who ascribed his power to cast out demons to the “prince of demons.” In fact, they accused Jesus of being possessed by Satan through “an unclean spirit.” This was a ridiculous accusation, so Jesus silences them, “How can Satan cast out Satan? If a kingdom is divided against itself, that kingdom cannot stand” (Mark 3:23-24).
Then Jesus tells them that all sins are forgivable, except one sin: blasphemy against the Holy Spirit. Even the sin of speaking a word against him is forgivable (Matt 12:31-32). For 2,000 years, from the time he started preaching the gospel, until today, and until he returns, unbelievers blaspheme his name. So blasphemy against God is “speaking a word” against God. It is desecrating God by openly insulting, mocking, dishonoring, or reviling him, just as the Jews did. For example, when people exclaim, “Oh, my God!” or when they use the name of God in cursing, it is blasphemy. In many ways, all of us have committed this sin. But we must not worry that we have committed the “unforgivable sin.”
Why then does Jesus call the Jews’ sin as blasphemy against the Holy Spirit, when they were speaking against him? This is because all of Jesus’ signs and wonders and words are also those of the Father and the Holy Spirit. His words and works are through the Spirit. Accusing him of being devil-possessed is the same as accusing God and the Spirit of the same thing.
Finally, this sin is not the sin of unbelief till death, because Jesus says that this sin is unforgivable “in this age or in the age to come.”