Jamieson, Fausset & Brown

children of the devil--(See on Jo1 3:8; Act 13:10). There is no middle class between the children of God and the children of the devil. doeth not righteousness--Contrast Jo1 2:29. he that loveth not his brother-- (Jo1 4:8); a particular instance of that love which is the sum and fulfilment of all righteousness, and the token (not loud professions, or even seemingly good works) that distinguishes God's children from the devil's.