Deuteronomy 32:28

For they [are] a nation void of counsel
This is said not of the Jews, whose character is given, ( Deuteronomy 32:6 ) ; and instances of their ingratitude, folly, and want of counsel and understanding, have been already mentioned, and punishment for the same inflicted on them, according to this prophetic song; so that the prophecy respecting them is issued, and another people are taken notice of, even their enemies, of whom the Jewish writers in general interpret these words, and what follows; and was true of the Gentiles, both of the Pagan sort of them, who took too much to themselves, and ascribed the destruction of the Jews, and their conquest of them, to themselves, and their idols; and of false Christians among them, when the Roman empire became Christian, such as expressed themselves in the language of the latter part ( Deuteronomy 32:27 ) , "our hand is high" which plainly showed them to be a people devoid of the true knowledge of the Scriptures, they should have made the men of their counsel, and have consulted; and of the Gospel of Christ, which is the counsel of God, as the Arians, Pelagians must be, or they would never imbibe and advance tenets so diametrically opposite thereunto:

neither [is there any] understanding is them;
of divine and spiritual things, of the Scriptures, and the doctrines of them; of the person of Christ, and his divine perfections, or they would never deny his deity; of the righteousness of God, of that which is required in the law, and revealed in the Gospel, or they would never set up a righteousness of their own for justification; and of themselves, their unrighteousness, impurity, and impotence to that which is good; or they would never so strongly assert the purity of human nature, and the power of man's freewill: God foreseeing all the folly, and want of counsel and understanding in the Gentile world, under different characters, preserved a remnant of the Jews as a standing admonition to them.