This passage can be best understood by looking at the original Greek words for "tarry", and "come." Here is the passage in view:

John 21:20-24 (King James Version, emphasis added)

Then Peter, turning about, seeth the disciple whom Jesus loved following; which also leaned on his breast at supper, and said, Lord, which is he that betrayeth thee? Peter seeing him saith to Jesus, Lord, and what shall this man do? Jesus saith unto him, If I will that he tarry<3306> till I come<2064>, what is that to thee? follow thou me. Then went this saying abroad among the brethren, that that disciple should not die: yet Jesus said not unto him, He shall not die; but, If I will that he tarry<3306> till I come<2064>, what is that to thee? This is the disciple which testifieth of these things, and wrote these things: and we know that his testimony is true.

Here are some Greek definitions for the words "tarry" and "come". I bolded parts of the definitions, I did this to emphasize the present reality in Christ that this passage is speaking of. Here are the definitions:

"TARRY"

Stong’s Greek Lexicon: "tarry" <3306>, (emphasis added)

3306. menw meno men'-o; a primary verb; to stay (in a given place, state, relation or expectancy):-- abide, continue, dwell, endure, be present, remain, stand, tarry (for), X thine own.

Online Bible Greek Lexicon: "tarry" <3306>, (emphasis added)

3306 menw meno men’-o

a root word; TDNT-4:574,581; v

AV-abide 61, remain 16, dwell 15, continue 11, tarry 9, endure 3, misc 5; 120

1) to remain, abide

1a) in reference to place

1a1) to sojourn, tarry

1a2) not to depart

1a2a) to continue to be present

1a2b) to be held, kept, continually

1b) in reference to time

1b1) to continue to be, not to perish, to last, endure

1b1a) of persons, to survive, live

1c) in reference to state or condition

1c1) to remain as one, not to become another or different

2) to wait for, await one

 

 

 

 

"COME"

Online Bible Greek Lexicon: "come" <2064>, (emphasis added)

2064 ercomai erchomai er’-khom-ahee

middle voice of a primary verb (used only in the present and imperfect tenses, the others being supplied by a kindred [middle voice] eleuyomai eleuthomai el-yoo’-thom-ahee, or [active] elyw eltho el’-tho, which do not otherwise occur); TDNT-2:666,257; v

AV-come 616, go 13, misc 13, vr come 1; 643

1) to come

1a) of persons

1a1) to come from one place to another, and used both of persons arriving and of those returning

1a2) to appear, make one’s appearance, come before the public

2) metaph.

2a) to come into being, arise, come forth, show itself, find place or influence

2b) be established, become known, to come (fall) into or unto

3) to go, to follow one

For Synonyms see entry 5818

 

By seeing how these words are defined in the original Greek, and seeing how they can be translated, this shows the normal progress of a born again believer. Once a person is born again, then they have at that moment received Life (1John 5:12 He that hath the Son hath life; and he that hath not the Son of God hath not life). Before a person is born again, they just exist with no Life. Once being born again, they now have Life. Since every born again believer has Life, they must come to know the Life they now have. They must come to know their Life (Christ). If they do not, then they continue as though they have not received Life. It is still "I" in the understanding. "I" remains and continues to be present in the understanding and therefore also in the outward actions. But the present reality in Christ declares: "Not I, but Christ" (Gal 2:20). This is so regardless of outward action. Now when Christ has His appearance in the heart of the believer, then the understanding is present: "Not I, but Christ." The believer begins to see that it is no longer "them", but the Life that is present is Christ. This leads to outwardly expressing Christ who is the Life of all believers. It is not an imitation of Christ, but it is Christ Himself having His expression. This is the normal progress of every born again believer, to live in the appearing of The Son and therefore express Him. This is what Paul calls apprehending "that for which also I am apprehended of Christ Jesus" (Phil 3:12). This is the purpose for every born again believer, it is to express the Life they have received.

In reference to our text, John 21:20-24, Jesus is simply letting Peter know that John will indeed remain until Christ appears. John will continue ignorantly of the Life he has received until the Life appears. John will go about with an understanding that it is still John, and therefore act as such. But when Christ appears, then John will realize that he has a Life that he knew nothing about, and then from that point he will begin to express the Life as much as he continues in the seeing and knowing of his Life who is Christ.