Matthew 12:30-31

He who is not with Me is against Me, and he who does not gather with Me scatters abroad. Therefore I say to you, every sin and blasphemy will be forgiven men, but the blasphemy against the [Holy] Spirit will not be forgiven men.
—Matthew 12:30-31, NKJV

Billy Graham said, “The unpardonable sin involves the total and irrevocable rejection of Jesus Christ. Resisting the Spirit is a sin committed by unbelievers. But it is a sin that, when carried on long enough, leads to eternal doom.”