This paragraph ties “light” and “darkness” to ordinary community relationships. The writer’s explicit test is not abstract insight but whether someone loves or hates a “brother” (vv. 9–11). A claim to be “in the light” is treated as false if it is paired with hatred (v. 9). Love, by contrast, is described as “remaining in the light,” producing steadiness rather than tripping up (v. 10).

The command is presented as both long-standing and freshly relevant. It is “old” because it is what they “heard from the beginning” (v. 7). It is also “new” because something about the present moment makes it newly true “in him and in you,” since darkness is already fading and “true light” is already shining (v. 8). The text frames this as a real, present shift, not only a future hope.

Where interpretation differs (only where needed)

What “from the beginning” means. Some read it as “from the beginning of your Christian life,” meaning the initial instruction these communities received when they first believed. Others read it as “from the beginning of Jesus’ message,” meaning the command goes back to what Jesus taught from the start.

Who “him” is in “true in him and in you.” Many take “him” to mean Jesus, so the command is “new” because it is embodied in Jesus and now reproduced in the community. Others think “him” points to God (or to the believer who claims light), emphasizing that the command’s truth shows up in God’s life and then in theirs.

Who “brother” includes. Some take “brother” mainly as a fellow believer, fitting the letter’s family language and internal community focus. Others think it naturally extends to people more broadly, since love is a central moral demand and hatred is condemned.

Why the disagreement exists

The wording is brief and assumes shared background. Phrases like “from the beginning” and “true in him and in you” can point in more than one direction without contradicting the immediate logic of the passage. Also, “brother” can be used narrowly (member of the faith family) or more broadly (neighbor), and the letter regularly addresses insiders while also speaking about moral realities that could apply more widely.

What this passage clearly contributes

• The writer makes an explicit textual claim that the command is not a novelty but the original message they received (v. 7).
• He also explicitly claims it is “new” in a meaningful sense tied to an already-started change: darkness is passing and true light is shining (v. 8). The theological inference is that the community lives in an “already happening” moral reality shaped by that light.
• He explicitly treats love/hatred toward a “brother” as a concrete indicator of whether someone is in light or in darkness (vv. 9–11). Whatever else “light” includes, it is not separated from relational posture.
• He explicitly links hatred with continued darkness, ongoing “walking” in darkness, and blindness-like disorientation (v. 11). Theological inference: hatred does not only break fellowship; it distorts moral perception.

John 13:34–35 provides a close parallel for the “new command” language, and 1 John 1:5–7 supplies the immediate backdrop for “light” as God’s moral reality.

new (kainēn)