What the Bible says
“Wherefore I say unto you, All manner of sin and blasphemy shall be forgiven unto men: but the blasphemy against the Holy Ghost shall not be forgiven unto men.”
Matthew 12:31 (KJV)
“Because they said, He hath an unclean spirit.”
Mark 3:30 (KJV)
“If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.”
1 John 1:9 (KJV)
What had just happened
Jesus had healed a man who was blind and mute because of a devil. The crowds wondered whether he was the Son of David. The Pharisees, unable to deny the miracle, said he cast out devils by Beelzebub, the prince of the devils (Matthew 12:22–24). Mark adds the key: Jesus said this because they claimed he had an unclean spirit.
Why this sin is different
Every other sin can be brought to God and forgiven. But the Holy Spirit is the one who shows us our need and draws us to Christ. To look at his work and deliberately call it evil is to shut the only door through which forgiveness comes. It is not a careless word spoken once; it is a heart that has decided to call light darkness.
If you are afraid you have committed it
The fear itself is a good sign. A heart that grieves over sin and wants God's forgiveness is a heart the Spirit is still working in. The promise stands for everyone who comes: if we confess our sins, he is faithful and just to forgive.
Common questions
What is blasphemy against the Holy Ghost?
In Matthew 12 and Mark 3 it is attributing the clear work of God's Spirit to Satan — a deliberate, hardened rejection of God's work rather than a single careless word.
Can a Christian commit the unforgivable sin?
Someone who is troubled about it and wants God's forgiveness shows the opposite of the hardened heart Jesus described. 1 John 1:9 promises forgiveness to all who confess.