Jamieson, Fausset and Brown on James 1:23

23. For--the logical self-deceit (Jas 1:22) illustrated.

not a doer--more literally, "a notdoer" [Alford]. The true disciple, say the rabbis, learns in order that he may do, not in order that he may merely know or teach.

his natural face--literally, "the countenance of his birth": the face he was born with. As a man may behold his natural face in a mirror, so the hearer may perceive his moral visage in God's Word. This faithful portraiture of man's soul in Scripture, is the strongest proof of the truth of the latter. In it, too, we see mirrored God's glory, as well as our natural vileness.