I have been fascinated to see, through my study of the history of exegesis of 1 Corinthians, the similarity of interpretations of verse 1:21, “For since, in the wisdom of God, the world did not know God through wisdom, it pleased God through the foolishness of what we preach to save those who believe.” Almost all exegetes use this verse to talk about God’s revelation through creatures; Nicholas of Lyra calls it the speculum creaturarum, the “mirror of creatures.” But they also talk about God as a wise teacher, who sees that his students failed to understand this mirror of creatures, and so tried another angle: the Incarnation. These are the comments from Theophylact of Ohrid (1055-1107), a Greek commentator:
Paul now gives the cause through which external wisdom [i.e., worldly wisdom] was made foolish. For since, in the wisdom available through visible creatures (for the heavens and the earth, and every creature proclaims the Creator) the world, that is, those whose mind is on the things of the world (who are clearly impeded through a wisdom that has its focus on fine speech), did not know God, it pleased God through the illiteracy of those preaching (which people think is foolishness, but really is not) to save those who believe. Therefore, though having the wisdom of God as a teacher, the Greeks, obviously gazing at creatures, did not know God through their wisdom of words, which is not, in fact, wisdom. (PG124: 580C)
As other commentators, Theophylact argues that there is a wisdom available through the creatures God has made, and that this can even be called the “wisdom of God.” The “Greeks,” however, those who only pay attention to what is visible and what makes for beautiful and persuasive speech (i.e., rhetoric), did not know God through this wisdom of creatures. Instead, they fell into idolatry and ignorance, failing to learn the lesson their ”teacher,” the wisdom of creation, had to teach them. A new lesson had to be prepared for them, then, in the preaching of the gospel, which God chose to operate through people without education (ιδιωτεια, what I’ve translated here as “illiteracy”) in order to get the Greeks to focus their attention somewhere else: not on “external wisdom,” but on spiritual, invisible wisdom.