For Little children (also in 3.18), see comments on 2.1.

Let no one deceive you expresses a warning against the false teachers. The form may be rendered ‘do not be deceived by any one,’ ‘take care that people do not deceive you,’ ‘do not follow those who try (or want) to lead you astray.’ For the verb deceive see comments on 1.8, where the reflexive form is used.

He who does right is righteous, or ‘if a person does what is right he (actually) is right,’ comes from the saying that a person’s activity is decisive for his quality; one is what one does. Probably this sentence is also aimed at a doctrine of the false teachers, who held that their acts did not matter, once they had reached the state of righteousness. For “to do right” (here and in verse 10) see comments on 2.29; for righteous (here and in verse 12) see comments on “just” in 1.9.

As he is righteous: except for the adjective this clause is identical with the similar as clause in 1 John 3.3, which see. The pronoun he, literally “that-one,” refers to Christ; compare comments on 2.6.

Quoted with permission from Haas, C., de Jonge, M. and Swellengrebel, J.L. A Handbook on The First Letter of John. (UBS Handbook Series). New York: UBS, 1972. For this and other handbooks for translators see here .