Because the foolishness of God
Not that there is any such thing as "foolishness" in God, nor the least degree of weakness in him; but the apostle means that which the men of the world esteem so, and therefore, by an ironical concession, calls it by those names; by which is intended either Christ, who, as crucified, is counted foolishness; yet he "is wiser than men": yea, even than Solomon, who was wiser than all men besides; Christ is greater than he in wisdom, having all the treasures of wisdom and knowledge in him; yea, in redemption by the blood of his cross, which is accounted such an egregious instance of folly, there is such a display of wisdom as surpasses all the wisdom of men and angels: and though he is, as crucified, esteemed as
the weakness of God,
yet in this respect,
is stronger than men;
stronger than the strong man armed; and has done that by his own arm, has brought salvation for his people, which neither men nor angels could ever have done: or all this may be understood of the Gospel of Christ, which is condemned as folly and weakness, and yet has infinitely more wisdom in it, than is to be found in the best concerted schemes of the wisest philosophers; and has had a greater influence on the minds and manners of men than theirs ever had; it is the manifold wisdom of God, and the power of God unto salvation. Moreover, these words may be applied to the saints, called in ( 1 Corinthians 1:27 )
the foolish and weak things of the world;
and yet even these, in the business of salvation, how foolish soever they may be in other respects, are wiser than the wisest of men destitute of the grace of God; and however weak they are in themselves, in their own esteem, and in the account of others, they are able to do and suffer such things, through the strength of Christ that no other men in the world are able to perform or endure. The phrases here used seem to be a sort of proverbial ones; and the sense of them is, that whatever, in things divine and spiritual, has the appearance of folly and weakness, or is judged to be so by carnal men, is wiser and stronger not only than the wisdom and strength of men, but than men themselves with all their wisdom and strength. It is very likely, that proverbial expressions of this kind, with a little alteration, were used by the Jews. The advice the young men gave to Rehoboam is thus paraphrased by the Targumist F15, (abad hytrwbg Nm apyqt ytwvlx) , "my weakness is stronger than the strength of my father"; which is very near the same with the last clause of this verse.
F15 In 2 Chron. x. 10.