Blasphemy (Greek blaptein, "to injure", and pheme, "reputation") signifies insulting or showing contempt or lack of reverence towards any person or thing worthy of exalted esteem.
The Bible speaks of blasphemy against the Holy Ghost as a sin which would not be forgiven in (Mat 12:31-32) saying:
(Mat 12:31 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.
(Mat 12:32) 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.
Blasphemy in the Old Testament against God as a whole could mean instantaneous death. Under the New Covenant, however, the bible speaks of blasphemy against the Holy Ghost only, as an unforgivable sin. In this context this article seeks to appreciate what scenarios lend to blasphemy against the Holy Ghost.
Examples of Blasphemy against God as a whole:
-Speaking in anyway to call God evil or to denounce the Holy ghost (Lev 24:11, 2Sa 12:14)
-To curse God (1Ki 21:13)
Examples of Blasphemy against the Holy ghost:
-Denying the works of the Holy Spirit, and giving Satan credit for that work. (Mat 12)
-If someone other than those of God, promoting themselves as operating in the Holy Ghost
-Speaking against someone who is anointed of God and saying the person has an unclean spirit. (Mar 3:30, Joh 10:33).