Matthew Poole and continuators on 1 John 2:29

29 If ye know that he is righteous, ye know that every one that doth righteousness, is born of him .

Lest he should be thought only sollicitious to preserve the right Notions among them, of the Christian Doctrine, as if that alone would suffice them for their Salvation and Blessedness, (which was the Conceit of the Gnosticks, touching their own Notions, that the entertaining of them, would save Men, whatsoever Men they were, or howsoever they liv'd) he subjoyns this serious Monition, If ye know, &c. intimating, that whatsoever they had of the Knowledge of God, would avail them nothing, if, whereas he is righteous, they were not transform'd by it into his likeness, and enabled thereby to do Righteousness, which alone would evidence their Divine Birth, since God hath no Children destitute of his Image, or who resemble him not.

Marginal references: Or, know ye.; Chap. 3.7▪ 10.