Adam Clarke on Romans 2:20

An instructer of the foolish, etc. - Ye believe the Gentiles to be babes and fools when compared with yourselves; that ye alone possess the only true knowledge; that ye are the only favourites of Heaven; and that all nations must look up to you as possessing the only form of knowledge, μορφωσιν της γνωσεως, the grand scheme and draught of all true science, of every thing that is worthy to be learned: the system of eternal truth, derived from the law. If, therefore, ye act not as becomes those who have such eminent advantages, it must be to your endless disgrace and infamy.