I think we should be clear on this though, as I’m sure you know how Mormons would respond to this. They believe that Christ’s atonement does not cover murder. If someone murders, they cannot be forgiven. Now, all Christians do believe that there is an unpardonable or unforgivable sin, i.e. blasphemy against the Holy Ghost:
***Matthew 12:31-32 (and the other verses that say the same thing)
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.
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.***
So, Christ’s atonement covers all sins except blasphemy against the Holy Ghost. Mormons, for whatever reason (perhaps related to the need for “restitution” for the repentance process), add murder to that. They also believe that murderers would have to suffer for that sin in spirit prison, then go to the telestial kingdom.