3 Nephi 18: 11

 
“And this shall ye always do to those who repent and are baptized in my name; and ye shall do it in remembrance of my blood, which I have shed for you, that ye may witness unto the Father that ye do always remember me. And if ye do always remember me ye shall have my Spirit to be with you.”
 
The prayer pronounced upon the sacrament reflects these same aspirations. However, this is not a petition in prayer, but a promise from the Lord. He affirms that for those who have “repented” of their sins, and “are baptized” in His name, He promises a result.
 
When, having done as He has asked, a person remembers His blood through this ordinance, bearing in mind that it was shed “for you” then you can properly “witness unto the Father.” The witness you make to the Father by this remembrance is that “ye do always remember Christ.”
 
This memorial before the Father, when done right, results in the promise of Christ that “ye shall always have His spirit to be with you.”
This is a covenant. This is the Lord promising. His word cannot fail. He is establishing for you the means by which you can have as your guide and companion His Spirit. His light. His presence in your life.
 
This is more intimate than touching His side, hands and feet. This is to have His Spirit within your touch at all times. You become an extension of Him, properly taking His name upon you. For you are then, indeed, a Christian.
 
He will christen or anoint you, not with the symbol of oil, but with the reality of His Spirit. This anointing is the real thing, of which the oil was meant only to testify.
 
The Holy Ghost was intended to become a companion at the time of baptism. The Spirit of Christ is intended to become a companion in your very person as well. When there are two members of the Godhead represented in your living person, then it is the Father who receives this testimony of you, about you, by you and for you. You become His, for these three are one.

There is more going on here than an ordinance and a testimony. This is the means by which a link is formed that can and will result in the Father taking that which is corruptible and changing it into that which is incorruptible. Though, like Christ, a man or woman may be required to lay down their life, they shall have power given them to take it up again. For that which has been touched by the incorruptible power of His Spirit cannot be left without hope in the grave. All such people die firm in the knowledge they are promised a glorious resurrection. (D&C 138: 14.)

This, then, is eternal life.