Growing up in church, I always heard about this “unforgivable sin.” I was told that if one attributes an act of the Holy Spirit to Satan, that person would never be forgiven. This idea stems from Mark 3:28-29 and their surrounding verses:
“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”
These verses come on the heels of the Pharisees accusing Jesus of being demon possessed. Jesus explains that this is impossible because Satan cannot drive out Satan (Mk 3:23). Then he moves into the verses above. It’s a pretty clear passage. Blaspheming the Holy Spirit, by attributing His works to Satan, is an unforgivable sin.
But we have to ask this question: what if someone does this once and then comes to faith in Christ? Will they remain unsaved even if they profess Jesus as Lord? Or, if a Christian wrongly interprets an act of God as an act of Satan, will they lose their salvation?
Each of these questions can be answered in the same way. The context of this verse is really important. These Pharisees are not simply skeptical about Jesus’ origins. Nor are they mistaken believers. They are actively pursuing rebellion against the God Whom they claim to serve by attacking His Son so violently and continuously. They are so wrong-headed in their thinking, so self-assured in their opinions, that they cannot see any other option then that Jesus is actually a servant of Satan. They rebuke Him for His faithfulness to God’s law above their own. The resist the evidence of His Sonship in the signs and wonders He performs. And they seek to destroy His life by any possible means.
Their sin is bound up in their active rebellion against God. They are unrepentant. They do not believe. They blind themselves to the truth.
They have been led to accuse Jesus of Satanic acts because they can think of no other alternative. They are utterly convinced that Jesus is not who He says He is.
That is the unforgivable sin. It undergirds their entire attitude. They simply do not believe in Jesus, and their unbelief has caused their terrible error in discernment.
All that to say, be of good cheer Christian. You are in no danger of committing such a sin if you continue to press into Jesus and find shelter under the wings of God. Do not fear, skeptical observer, Jesus welcomes all who come to Him. Do not wait another moment. seek Jesus with all your heart and there is no sin that He will not forgive.