D&C 132:27; “The blasphemy against the Holy Ghost, which shall not be forgiven in the world nor out of the world, is in that ye commit murder wherein ye shed innocent blood, and assent unto my death, after ye have received my new and everlasting covenant, saith the Lord God; and he that abideth not this law can in nowise enter into my glory, but shall be damned, saith the Lord.”
John 19:30; “When Jesus therefore had received the vinegar, he said, It is finished: and he bowed his head, and gave up the ghost.”
This Mormon teaching is telling you that murder is blasphemy against the Holy Ghost and cannot be forgiven. Praise God for His Son! The words He spoke “It is finished” is comfort for my soul.