who in time past were no people, but now are God's people, who had not obtained mercy, but now have obtained mercy.

 This food of the word is unadulterated (adolos, G97) . That is to say, there is not the slightest admixture of anything evil in it. Adolos ( G97) is an almost technical word to describe corn (American: grain) that is entirely free from chaff or dust or useless or harmful matter. In all human wisdom there is some admixture of what is either useless or harmful; the word of God alone is altogether good. 