Romans 2:20 Meaning

18And knowest his will, and approvest the things that are more excellent, being instructed out of the law;

19And art confident that thou thyself art a guide of the blind, a light of them which are in darkness,

20An instructor of the foolish, a teacher of babes, which hast the form of knowledge and of the truth in the law.

21Thou therefore which teachest another, teachest thou not thyself? thou that preachest a man should not steal, dost thou steal?

22Thou that sayest a man should not commit adultery, dost thou commit adultery? thou that abhorrest idols, dost thou commit sacrilege?