1 John 3:4
The context
The letter has been answering a group that claimed to be without sin and to have fellowship with God while living otherwise. Here the argument turns to definition. The sentence is short, almost a formula, and it functions as a premise for what follows about the Son's appearing to take away sins and destroy the works of the devil.
What it establishes
It establishes that sin is not a private matter of taste or self-assessment but a violation of a standard outside the person. The definition is moral and relational, and it grounds the letter's insistence that conduct matters.
What it does not establish
It is not a complete definition of sin. The Bible also speaks of sin as missing a mark, as debt, and as unfaithfulness, and this verse supplies none of those. Nor does it specify whose law is in view, or how a Gentile reader should map it.
Short note, first pass, October 2026. Corrections welcome.
Cited in these answers
Part of Scripture, Opened — the exegetical layer behind every citation on this site. Scripture quotations are from the ESV.