1 Corinthians 15:33
1 Corinthians 15:3333Do not be deceived: “Bad company corrupts good character.”
This is the flagship JW proof-text for the categorical separation from non-Witnesses. The Watchtower applies "bad associations spoil useful habits" to friendships at school, work, sports, hobbies, and the neighbourhood — anyone outside the organisation counts as a "bad association," even when their personal conduct is unblemished. The 2013-02-15 Watchtower compares friendship with non-Witnesses to a small amount of pollution contaminating clean water; the 2015-08-15 Watchtower instructs that "we should not become close friends with those who do not obey God."
Paul is quoting Menander's comedy Thais (frag. 218) — a well-known Greek proverb — and dropping it into a doctrinal argument against resurrection-deniers inside the Corinthian congregation. The context is verses 12-34: some at Corinth are denying the resurrection (v.12), and Paul fears their teaching will erode the congregation's hope (v.32 — "if the dead are not raised, let us eat and drink"). The "bad associations" he warns against are the resurrection-deniers within the church, not non-Christian neighbours. Paul then urges the congregation to "sober up" and "stop sinning" (v.34). Read in context, the verse is a doctrinal rebuke of insiders, not a categorical ban on outside relationships. Jesus' own pattern — eating with tax collectors and sinners (, ) — refutes the categorical reading, as does Paul's own clarification at 1 Cor 5:10 that avoiding all non-Christian sinners would require leaving the world.
The NWT renders the Greek phthora ēthē chrēsta homiliai kakai as "bad associations spoil useful habits" — softening the moral weight of ēthē (character, morals) to the behavioural register of "habits." Standard translations read "bad company corrupts good morals" (ESV) or "good character" (NASB). The shift is subtle but matters in practice: Paul's proverb is about moral corruption of the inner person; "useful habits" reads like a behavioural warning that maps neatly onto the Watchtower's concerns about field-service, meeting attendance, and visible loyalty. The Greek word is doing heavier work than the English suggests.