Here are some thoughts from my reading the three Letters of John. We are also reading them at my Goodreads Catholic Thought book club, so you might see some back and forth exchanges.
What strikes me early on in the first letter is how the motifs are similar with John’s Gospel. Here’s the first chapter.
1 What was from the beginning, what we have heard, what we have seen with our eyes, what we looked upon and touched with our hands concerns the Word of life—
2 for the life was made visible; we have seen it and testify to it and proclaim to you the eternal life that was with the Father and was made visible to us—
3 what we have seen and heard we proclaim now to you, so that you too may have fellowship with us; for our fellowship is with the Father and with his Son, Jesus Christ.
4 We are writing this so that our joy may be complete. God is Light.
5 Now this is the message that we have heard from him and proclaim to you: God is light, and in him there is no darkness at all.
6 If we say, “We have fellowship with him,” while we continue to walk in darkness, we lie and do not act in truth.
7 But if we walk in the light as he is in the light, then we have fellowship with one another, and the blood of his Son Jesus cleanses us from all sin.
8 If we say, “We are without sin,” we deceive ourselves, and the truth is not in us.
9 If we acknowledge our sins, he is faithful and just and will forgive our sins and cleanse us from every wrongdoing.
10 If we say, “We have not sinned,” we make him a liar, and his word is not in us.
Compare with the opening lines of John’s Gospel:
1 In the beginning was the Word, and the Word was with God, and the Word was God.
2 He was in the beginning with God.
3 All things came to be through him, and without him nothing came to be. What came to be
4 through him was life, and this life was the light of the human race;
5 the light shines in the darkness, and the darkness has not overcome it.
“Beginning,” “Word,” “light,” “darkness,” “God is light.” The words overlap. I’m not going to copy back and forth, but read chapters 15 and 17 where Jesus gives his discourses and see how many themes and phrasing are shared between the Gospel and this letter. Now this is in translation, so one can't be definitive about rhythm, but even the rhythm of the language seems to be very similar.
Presumably there are always questions to who actually wrote the Gospels, and of course we don’t know for sure that the author of the fourth Gospel and these letters was actually St. John, but I don’t think there can be any doubt that it’s one and the same person. By the way, I’m convinced it’s St. John the Evangelist.
Rhetorically I find that first chapter fascinating. Here’s that sentence without any line breaks:
“What was from the beginning, what we have heard, what we have seen with our eyes, what we looked upon and touched with our hands concerns the Word of life—for the life was made visible; we have seen it and testify to it and proclaim to you the eternal life that was with the Father and was made visible to us—what we have seen and heard we proclaim now to you, so that you too may have fellowship with us; for our fellowship is with the Father and with his Son, Jesus Christ.”
Four parallel noun phrases beginning with “what” starts the sentence. The last three emphasize that “we”—and who “we” is supposed to include is undetermined—physically knew and can testify to the “Word” having come to earth and was made “visible.” And then tells you why: so that “you” too—and “you” also being undetermined—may have fellowship with God. He actually testifies three times in that sentence. The first leading up to the dashed off section, the second inside the dashed section, and then even a third time at the beginning of the clause after the dashed section.
Indeed, repetition is a wonderful, poetic device here. How many times does he repeat phrasings and words: “heard,” “seen,” “visible,” “fellowship,” “light,” “darkness,” “God is light,” “sin,” and so on. And yet it never feels like boring writing.
The first letter is just packed with theological points. I tend to reduce John’s letters down to love, love, love. And rightly so because love is at the central part of his theology. Love is so central, he could have been one of the Beatles. “All you need is love.” Haha, but that’s simplifying. John makes some complex theological points, and I’m probably not qualified to fully elucidate them. Look at the opening verses from chapter three.
1 See what love the Father has bestowed on us that we may be called the children of God. Yet so we are. The reason the world does not know us is that it did not know him.
2 Beloved, we are God’s children now; what we shall be has not yet been revealed. We do know that when it is revealed we shall be like him, for we shall see him as he is.
3 Everyone who has this hope based on him makes himself pure, as he is pure.
Through our baptism—or perhaps something less formal, such as identifying ourselves as Christians—we have become children of God, which elsewhere I think is referred to as adoption. We then become the heirs of God and ultimately joined with Him.
It is said that in John (both the Gospel and Letters) creates strict demarcations, perhaps even polarized dichotomies. Here he divides children of God with those who are not, those that know Him and those that don’t, those that are pure and those that are not.
4 Everyone who commits sin commits lawlessness, for sin is lawlessness.
5 You know that he was revealed to take away sins, and in him there is no sin.
6 No one who remains in him sins; no one who sins has seen him or known him.
7 Children, let no one deceive you. The person who acts in righteousness is righteous, just as he is righteous.
8 Whoever sins belongs to the devil, because the devil has sinned from the beginning. Indeed, the Son of God was revealed to destroy the works of the devil.
9 No one who is begotten by God commits sin, because God’s seed remains in him; he cannot sin because he is begotten by God.
10 In this way, the children of God and the children of the devil are made plain; no one who fails to act in righteousness belongs to God, nor anyone who does not love his brother.
11 For this is the message you have heard from the beginning: we should love one another,
12 unlike Cain who belonged to the evil one and slaughtered his brother. Why did he slaughter him? Because his own works were evil, and those of his brother righteous.
Look at the demarcations here: Those who commit sins and those that do not. Those who were privileged to have Him revealed and those who were not. Those who are righteous and those who are not. Those who belong to the devil (because they sin) and those who do not. Those who love one another and those who do not. There doesn’t seem to be any middle ground. I don’t know about you, but I still sin. Perhaps he’s referring to mortal sin. He goes on to augment his point.
13 Do not be amazed, [then,] brothers, if the world hates you.
14 We know that we have passed from death to life because we love our brothers. Whoever does not love remains in death.
15 Everyone who hates his brother is a murderer, and you know that no murderer has eternal life remaining in him.
16 The way we came to know love was that he laid down his life for us; so we ought to lay down our lives for our brothers.
17 If someone who has worldly means sees a brother in need and refuses him compassion, how can the love of God remain in him?
18 Children, let us love not in word or speech but in deed and truth.
There is another dichotomy: those who are in death (because they do not love) and those that are in life. And that leads to his central point.
19 [Now] this is how we shall know that we belong to the truth and reassure our hearts before him
20 in whatever our hearts condemn, for God is greater than our hearts and knows everything.
21 Beloved, if [our] hearts do not condemn us, we have confidence in God
22 and receive from him whatever we ask, because we keep his commandments and do what pleases him.
23 And his commandment is this: we should believe in the name of his Son, Jesus Christ, and love one another just as he commanded us.
24 Those who keep his commandments remain in him, and he in them, and the way we know that he remains in us is from the Spirit that he gave us.
How do we know if we are children of God? Because if we have love in our hearts, then we will follow His commandment to love one another as He loved in the world. We will know this through the Holy Spirit.
I’m not sure if my exegesis is correct or complete, but I hope I’ve at least highlighted the complexity of John’s thought. It’s more complicated than a Beatles song. ;)