The sin of denying the Holy Ghost, a sin that cannot be forgiven.

Blasphemy against the Holy Ghost shall not be forgiven unto men, Matt. 12: 31-32 (Mark 3: 29; Luke 12: 10). It is impossible for those who were made partakers of the Holy Ghost to renew them again unto repentance, Heb. 6: 4-6. If we sin wilfully after we have received the knowledge of the truth, there remaineth no more sacrifice for sins, Heb. 10: 26. If ye deny the Holy Ghost and know that ye deny it, this is a sin which is unpardonable, Alma 39: 5-6 (Jacob 7: 19). They have no forgiveness, having denied the Only Begotten Son, having crucified him unto themselves, D&C 76: 30-35. The blasphemy against the Holy Ghost shall not be forgiven, which is shedding innocent blood after ye have received my new and everlasting covenant, D&C 132: 26-27.