Though 1 John is anonymous, tradition associates it with the Apostle John or perhaps Elder John who are both connected to churches in Asia Minor in the late first century. Whatever the case (and I will call the author “John”), it is rather immaterial to the themes and meaning of the text.
1 John begins and ends like a “tract,” or even homily (sermon). It does not have the form of a letter (unlike 2 John and 3 John). It is more like a community handbook intended for a region of congregations. We might imagine the author seeks to provide perspective given the recent turmoil congregations in Asia Minor (or a larger region) have experienced. Consequently, the “letter” (I use term accommodatively) functions as a handbook for communities as a way of orienting them toward the central truths that should shape their communal life.
These congregations have recently suffered a division where some left and established alternative communities. They seceded from the original congregations in order to maintain their own theological agenda. At the core of this secession was the belief that Jesus did not come in the flesh, or what is called “Docetism” in the early church (1 John 2:19-22; 4:1-2, 7). Interestingly, when Ignatius of Antioch pens letters to several congregations in Asia Minor around 112 CE, he recognizes there were competing congregations in the area, and some of those congregations were “Docetists,” that is, they denied the Son of God had come in the flesh. The author of 1 John considers this a denial of a central truth of the Christian community, and bids the secessionists farewell as long as they persist in this belief.
John addresses this situation by reminding these churches of two important truths, which fundamentally ground Christian communities. These two truths organize the “letter,” which is an exposition and application of these truths to the post-secessionist situation in which these churches find themselves.
The first truth is: “God is light” (1 John 1:5). This is, as John writes, “the message we have heard from him and declare to you.” It is, literally, “the announcement” we “announced.” It is a fundamental message of the Christian community.
This is intimately connected to the claim that Jesus has come in the flesh. God, in whom there is no darkness, has entered the world through the incarnation (taking on flesh) as light in the midst of darkness. Through this light, God reveals eternal life, shares eternal life, and cleanses humanity from sin so that humanity might participate in that life and light. John believes the claim that “Jesus has come in the flesh” is essential to the revelation of this truth, that is, “God is light.”
1 John 1:5-3:10 develops this theme. The light of God is revealed in the incarnate Jesus, who calls us into a life of purity, truth, and righteousness as we walk in the light as Jesus lives and reveals that light. Consequently, we recognize the Christianity community is fundamentally different in its values and mission than the rest of the “world” (as John uses the term) precisely because this community is founded on the light that Jesus revealed through coming in the flesh.
The second truth is: “God is love” (1 John 4:8, 16). The second “announcement,” that “we should love one another,” is grounded in this truth (1 John 3:11). Indeed, this is the “new commandment” that shapes the Christianity community (1 John 2:7-8).
We love one another because we participate in the life of God who is love. We know the love of God because God sent the Son into the world by which God loved us so that we might learn to love others. When the love of God fills our hearts, we love each other; when we know God, or experience God, or participate in the life of God, then we also love each other as God has loved us. The second “announcement,” then, is actually an exposition of this truth: “God is love.”
1 John 3:11-5:12 develops this theme. The love of God is revealed in the life and death of Jesus, who calls us to love each other just as he has loved us. In fact, this is fundamentally what it means to walk in the light because just as God is light so also God is love. When we walk in the light, we love one another. Again, this is how the community of Jesus is fundamentally different from the “world.”
These two truths—“God is light” and “God is love”—are revealed in the incarnation, ministry, and death of Jesus the Messiah. The church confesses Jesus as the Messiah who came in the flesh, and this coming revealed the light and love of God. This is the heart of the Christian faith, and it is this message (“announcement”) that makes a community an authentic, living embodiment of God in the world.
Indeed, as the prologue (1 John 1:1-4) and epilogue (1 John 5:13-21) make clear, Jesus is the “eternal life” through whom God is revealed and through whom we participate in the life of God. We enjoy “eternal life” as we participate in the light and love of God experienced and known through Jesus. Consequently, we “know” that light and love when we entrust ourselves to God through Jesus and become children of God (1 John 5:13). As children, we walk in the light of God, and we love each other.