Giving Satan the credit for what is actually the work of the Holy Spirit as demonstrated through Jesus Christ. This sin is also known as blasphemy against the Holy Spirit.
What Is the Unpardonable Sin?
The unpardonable sin must be defined by its context. In Matthew 12:31–32 and Mark 3:28–30, Jesus had just cast a demon from a man who was blind and mute. Unmistakable evidence of God's power had just happened. But the Pharisees, with stubborn unbelief, gave credit for this display of God’s power to Beelzebul, the devil (Matthew 12:24).
Other scriptures record this kind of response from many Jews. The suspicion was that Jesus was performing miracles by the power of the devil (Matthew 9:34; Luke 11:14–20; John 7:20; 8:48, 52; 10:20). A group of Jews, mostly Pharisees, were giving the devil credit for the work of the Spirit Jesus was demonstrating.
They committed the unpardonable sin by saying that Jesus’s miracles were performed with power from Beelzebul, the devil. Put simply, they sinned by boldly saying and believing that Jesus’s works were the work of Satan instead of the Holy Spirit. Many Jews continued this false story about Jesus long after his death. They did not deny that he did miracles. Instead, they said he did miracles by the power of the devil.
What Is Not the Unpardonable Sin?
The unpardonable sin is different from when the people of Israel disobeyed God. Israel's disobedience resulted in the eternal judgment of many people and the loss of God’s blessing for a time. But this was not the unpardonable sin.
The "sin unto death" mentioned by John (1 John 5:16–17) is not the unpardonable sin. A redeemed and forgiven person (Ephesians 1:7) has cleansing for present and future sin (1 John 1:7) and eternal life (John 3:16). This person cannot commit an unpardonable sin. But those who commit the "sin unto death" are all Christians. First John 5:16 says the person who commits the "sin unto death" is a "brother" in Christ.
The unpardonable sin is not rejection of the Lord Jesus until the rejecter dies in his unbelief. This sin will not be forgiven throughout eternity. But the sin of rejection is not the same sin as the one Jesus condemned as unpardonable. "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 one to come." (Matthew 12:32).
Many passages repeat the warning that unbelief in the Savior results in eternal death (John 3:18, 36; 1 John 5:12; Revelation 20:15; 21:8). These Scriptures do not directly speak of the unpardonable sin. Jesus said that a person could be an unbeliever and even speak against him, yet not be guilty of the unpardonable sin.