Shared ground
This paragraph ties God’s love to a new family identity: believers are called “children of God,” and the writer treats that as a real present status (“now we are children of God”). That identity helps explain a social mismatch: “the world” does not recognize believers, and the reason given is that it did not recognize “him” first.
The passage also holds together “already” and “not yet.” Believers already belong to God’s family, yet their future condition is still partly hidden. One future point is stated with confidence: when “he” is revealed, believers will be like him, connected to seeing him “as he is.”
Finally, future hope is not presented as passive. The writer says that having “this hope set on him” is linked to present cleansing (“purifies himself”), with Christ’s purity as the measure (“as he is pure”). 1 John 3:1
Where interpretation differs (only where needed)
Who is “him/he”? Many read “him” in v.1 (“the world didn’t know him”) as Jesus, since the world’s failure to recognize Jesus is a central theme in early Christian memory, and v.2 speaks of “when he is revealed” and “seeing him.” Others argue “him” in v.1 could refer to God the Father, because the paragraph begins with “the Father” and being “children of God.” A mixed reading is also possible: v.1 points mainly to God, while v.2–3 clearly focus on the Son’s appearing.
What does “purifies himself” mean here? Most interpreters take it as moral cleansing—ongoing choices that align with Christ’s purity—because it is grounded in “hope” and becomes a bridge into the next section about sin and righteousness (3:4ff.). Some note the wording can sound like cleansing language used for ritual purity, and suggest the phrase may echo those ideas while still aiming at lived moral integrity.
Why the disagreement exists
The passage uses short pronouns (“him/he”) without restating names, and it moves quickly between Father-focused language (v.1) and future “appearing” language (v.2) that sounds strongly Christ-centered. Also, “purify” can carry more than one shade of meaning, and the letter will soon focus on concrete behavior, encouraging readers to ask how broad or specific this “purifying” is.
What this passage clearly contributes
Explicitly, it claims: (1) the Father’s love is shown in calling believers God’s children; (2) the world’s non-recognition of believers follows its non-recognition of “him”; (3) believers already are God’s children; (4) their future state is not yet disclosed; (5) at “his” revealing they will be like him; (6) that likeness is connected to seeing him as he is; (7) hope oriented toward him is linked to present self-purification, measured by his purity. Theologically inferred (but strongly suggested) is an “already/not yet” pattern: secure belonging now, fuller transformation later at Christ’s appearing.