Lest he should be thought only solicitous to preserve among them the right notions of the Christian docrine, as if that alone would suffice them for their salvation and blessedness, (which was the conceit of the Gnostics, touching their own notions, that the entertaining of them would save men, whatsoever men they were, or howsoever they lived), he subjoins 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 transformed 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.
Related Commentaries of 1 John 2:29
1 John 2:29
29 If ye know that he is righteous, ye know that every one that doeth righteousness is born of him.