"blotted out"

I haven't noticed this detail before. In Alma 5, Alma-2 is preaching to the people in Zarahemla. Verse 57 reads:

And now I say unto you, all you that are desirous to follow the voice of the good shepherd, come ye out from the wicked, and be ye separate, and touch not their unclean things; and behold, their names shall be blotted out, that the names of the wicked shall not be numbered among the names of the righteous, that the word of God may be fulfilled, which saith: The names of the wicked shall not be mingled with the names of my people; For the names of the righteous shall be written in the book of life, and unto them will I grant an inheritance at my right hand.

I think this is refering to something that happened a couple of decades earlier that is described in Mosiah 26. Alma-2's father, Alma-1, was the high priest of the church back then and there were some issues about members who had fallen into transgression that Alma-1 inquired the Lord about. The quoted verses below are part of the Lord's response.

24 For behold, in my name are they called; and if they know me they shall come forth, and shall have a place eternally at my right hand...

32 Now I say unto you, Go; and whosoever will not repent of his sins the same shall not be numbered among my people; and this shall be observed from this time forward...

36 And those that would not confess their sins and repent of their iniquity, the same were not numbered among the people of the church, and their names were blotted out.

Another example of internal consistency.

The expression, "blotted out", is also used by King Benjamin as part of a chiasmus in Mosiah 5

A that whosoever shall not take upon him the name of Christ 
   B must be called by some other name; 
      C therefore, he findeth himself on the left hand of God.
         D And I would that ye should remember also, that this is the name 
            E that I said I should give unto you that never should be blotted out, 
               F except it be through transgression; therefore, 
               F' take heed that ye do not transgress, 
            E' that the name be not blotted out of your hearts. 
         D' I say unto you, I would that ye should remember to retain the name 
      C' written always in your hearts, that ye are not found on the left hand of God, 
   B' but that ye hear and know the voice by which ye shall be called, 
A' and also, the name by which he shall call you.

It is interesting to compare the use of this expression here with Alma 7:13

the Son of God suffereth according to the flesh that he might take upon him the sins of his people, that he might blot out their transgressions according to the power of his deliverance

King Benjamin says that the name of Christ will be blotted out of our hearts if we transgress. But Alma says that Christ has the power to blot out our transgressions. The difference is obviously repentance. If we don't repent, our transgressions will blot out Christ, but if we repent, Christ will blot out our transgressions!