Blasphemy = blas’-fe-mi (blasphemia): In classical Greek meant primarily “defamation” or “evil-speaking” in general; “a word of evil omen,” hence, “impious, and irreverent speech against God”; “the unpardonable sin”.
THE BIBLE SAYS:
He that is not with me is against me; and he that gathereth not with me scattereth abroad.
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.
And whosoever speaketh a word against the Son of man, it shall be forgiven him: but whosoever speaketh against the Holy Ghost, it shall not be forgiven him, neither in this world, neither in the world to come.
~ Matthew 12:30-32