The ESV translation is such that a single document from the writer would fulfill both sets of phrases:
I am writing to you, fathers… (2:13)
I write to you, fathers… (2:14)
As noted in the answers of Jas 3.1 and Joseph, this has the effect of focusing on repetition making style an emphasis and drawing attention to the reason stated “because…”
Many translations render the second set as “I have written…” [1 John 2:14] This makes a clearer statement the Epistle is intended to be considered in conjunction with a second (earlier) document.
David Smith has written:
It is beyond reasonable doubt that the Epistle and the Gospel are from the same pen. “The identity of authorship in the two books,” says Lightfoot, “Though not undisputed, is accepted with such a degree of unanimity that it may be placed in the category of acknowledged facts.” And they have a very intimate connection. This is abundantly apparent from the internal evidence. The Epistle opens with a reference to the Gospel-narrative, and there is an unmistakable relation between 1 John v. 13 and John xx. 31 (see commentary). Indeed the Epistle throughout has the Gospel as its background and is hardly intelligible without it. 1
This poetic or stylistic element is placed in the opening of the Epistle, before identifying the situation which caused the Epistle to be written (the false teaching and split). One effect of this element is to make clear the Epistle is intended for the entire church. When taken literally, the Epistle is written to the family unit, even the youngest members. However, reading the Epistle in conjunction with the Gospel means this passage should also be considered in that light:
John's Epistle: I am writing to you…
John's Gospel: I have written to you…2
The connections between Epistle and Gospel are not limited to language, construct, and concepts: there is an experiential connection between the two. For example, the Epistle begins:
This is what we proclaim to you: what was from the beginning, what we have heard, what we have seen with our eyes, what we have looked at and our hands have touched (concerning the word of life— (1:1) 3
"Word" draws on the language of the Gospel of John and "word of life" draws on the experiences of the disciples recorded in the Gospel of John:
After this many of his disciples quit following him and did not accompany him any longer. So Jesus said to the twelve, “You don’t want to go away too, do you?” Simon Peter answered him, “Lord, to whom would we go? You have the words of eternal life. (John 6:66-68)
The Epistle opens with the writer paraphrasing Peter’s response to Jesus asking a question of the twelve. 4 The experiential context of the question is that it is asked after an exodus of disciples over Jesus teaching them they must eat His flesh and drink His blood. The Gospel event, some disciples abandoning Jesus over the issue of His flesh and His blood, is the same situation the Epistle addresses: a split in the Church over the issue of whether Jesus came in the flesh.
When the Epistle is read in the light of the Gospel, the Gospel describes the disciples in situations similar to those reading the Epitle. The division is nothing new; disciples walked away from Jesus over this same issue when He was alive and with them. The Epistle is not new instruction: it is drawn fro Gospel events and it is the Gospel which provides the guidance to a right response: continue to abide in the Word to know the truth and the source of what Jesus taught:
Then Jesus said to those Judeans who had believed him, “If you continue to follow my teaching, you are really my disciples and you will know the truth...” (John 8:31-32)
If anyone wants to do God’s will, he will know about my teaching, whether it is from God or whether I speak from my own authority. (John 7:17)
The Epistle summarizes the Gospel with a focus relevant to the current issue.
The opening of the Epistle (1:1-4) states there are others in the church whom the Epistle is written to that were with the writer. So there is more than one original disciple in the church. If that is true, then the others can validate the message in the Epistle and they were witnesses to the events recorded in the Gospel. So they, like the writer, were the original believers. They have know Jesus from the beginning, and before the Gospel was written:
I am writing to you, fathers, that you have known him who has been from the beginning… (2:13)
I have written to you, fathers, that you have known him who has been from the beginning… (2:14)
“Fathers” is used symbolically for that group. As original disciples, their condition is not only the same as the writer's, it has remained constant throughout. They are "fathers" since their witness has added family members to the Body of Christ:
For though you may have ten thousand guardians in Christ, you do not have many fathers, because I became your father in Christ Jesus through the gospel. (1 Corinthians 4:15)
“Young people” (or young men) makes use of the analogy to the family unit; it is used to represent individuals who became believers as a result of the witness of the original disciples (the “fathers”):
I am writing to you, young people, that you have conquered the evil one. (2:13)
…I have written to you, young people, that you are strong, and the word of God resides in you, and you have conquered the evil one. (2:14)
This is also a connection found in the Epistle's introduction and the Gospel:
What we have seen and heard we announce to you too, so that you may have fellowship with us (and indeed our fellowship is with the Father and with his Son Jesus Christ). Thus we are writing these things so that our joy may be complete. (1 John 1:3-4)
“I am not praying only on their behalf, but also on behalf of those who believe in me through their testimony, that they will all be one, just as you, Father, are in me and I am in you. I pray that they will be in us, so that the world will believe that you sent me. (John 17:20-21)
The unity Jesus prays for (Gospel) is the same unity the writer seeks (Epistle). In both cases the unity is based on the witness of the original disciples. In effect the writer opens by saying, "I and the others who were with Jesus the night He died want you to have the fellowship He prayed for."
Finally, there are two types of “little children.”
I am writing to you, little children (τεκνία), that your sins have been forgiven because of his name. (2:12)
I have written to you, children (παιδία), that you have known the Father… (2:14)
The Epistle uses τεκνία and παιδία as they are used in the Gospel of John:
τεκνία: Children, I am still with you for a little while. You will look for me, and just as I said to the Jewish religious leaders, ‘Where I am going you cannot come,’ now I tell you the same. (13:33)
παιδία: So Jesus said to them, “Children, you don’t have any fish, do you?”… (21:5)
During His final meal and before all of the disciples deserted Him, Jesus addressed His disciples as τεκνία. After the crucifixion and resurrection, Jesus prepares breakfast and calls His disciples παιδία.
The writer of the Epistle and the Gospel also draws on the other Gospels:
But Jesus called for the children, saying, “Let the little children (παιδία) come to me and do not try to stop them, for the kingdom of God belongs to such as these. I tell you the truth, whoever does not receive the kingdom of God like a child (παιδία) will never enter it.” (Luke 18:16-17)
and so were James and John, Zebedee’s sons, who were Simon’s business partners. Then Jesus said to Simon, “Do not be afraid; from now on you will be catching people.” (Luke 5:10)
When understood with the other wirtten records of the life of Jesus, the point of the question (in the Gospel of John) takes on added significance: “Children (παιδία), you don’t have any fish, do you?” Jesus finds the disciples trying to catch fish (their previous occupation) not at work to make new disciples (their current assignment).
Therefore the term τεκνία may be understood as a disciple who is less mature than a παιδία and/or is not making new disciples.
There are many other aspects that can be taken from this section. For instance, the fathers, young poeple, and little children indicate diversity, both physical age and spiritual maturity within the church. Repetition also reinforces the concept of continuity within the group; despite the division fathers, young people, and both types of little children are present.
While the stylistic element may be present, given the serious nature of the issue, it is unlikely the writer of the Epistle would place style over content in what is essentially part of the introduction. Rather, the message of the Epistle is simply: "What I have written about Jesus in the Gospel is true and the Holy Spirit promised in the Gospel affirms the truth in both the Gospel and this letter."
1. David Smith, The Expositor’s Greek Testament, volume 5 p 154 Expositor's Greek Testament
2. The structure of this section is therefore purposeful to affirm the existence of fourth Gospel and in doing so also affirms the existence of the Synoptics. That is, this section of the Epistle affirms the historicity of all four Gospel narratives.
3. All Scripture from the New English Translation except as noted.
4. Using Peter's words is another way to reinforce the point they were an original disciple.