1 John 5:21
5:21 Little children, guard yourselves from idols. 1
1 tc Most later mss (P Ï) have ἀμήν (amhn, “amen”) at the end of this letter. Such a conclusion is routinely added by scribes to NT books because a few of these books originally had such an ending (cf. Rom 16:27; Gal 6:18; Jude 25). A majority of Greek witnesses have the concluding ἀμήν in every NT book except Acts, James, and 3 John (and even in these books, ἀμήν is found in some witnesses). It is thus a predictable variant. Further, the earliest and best witnesses, along with several others (א A B Ψ 33 323 630 1505 1739 al sy co), lack the inoffensive particle, rendering its omission as the authentic reading.
sn The modern reader may wonder what all this has to do with idolatry. In the author’s mind, to follow the secessionist opponents with their false Christology would amount to idolatry, since it would involve worshiping a false god instead of the true God, Jesus Christ. Thus guard yourselves from idols means for the readers to guard themselves against the opponents and their teaching.