Jamieson, Fausset and Brown on 1 Corinthians 1:27

27. the foolish things--a general phrase for all persons and things foolish. Even things (and those, too, foolish things) are chosen by God to confound persons, (and those too persons who are wise). This seems to me the force of the change from neuter to masculine.

to confound--The Greek is stronger, "that He might confound (or put to shame)." God confounds the wise by effecting through His instruments, without human wisdom, that the worldly wise, with it, cannot effect, namely, to bring men to salvation.

chosen ... chosen--The repetition indicates the gracious deliberateness of God's purpose (Jas 2:5).