Here is a really great commentary talking about just that. It's not the fact that God is foolish or weak but even what appears so to us is still so much better than our human efforts...
Because the foolishness of God - That which God appoints, requires, commands, does, etc., which appears to people to be foolish. The passage is not to be understood as affirming that it is really foolish or unwise; but that it appears so to people - Perhaps the apostle here refers to those parts of the divine administration where the wisdom of the plan is not seen; or where the reason of what God does is concealed.
Is wiser than men - Is better adapted to accomplish important ends, and more certainly effectual than the schemes of human wisdom. This is especially true of the plan of salvation - a plan apparently foolish to the mass of people - yet indubitably accomplishing more for the renewing of people, and for their purity and happiness, than all the schemes of human contrivance. They have accomplished nothing toward people's salvation; this accomplishes everything. They have always failed; this never fails.
The weakness of God - There is really no weakness in God, any more than there is folly. This must mean, therefore, the things of his appointment which appear weak and insufficient to accomplish the end. Such are these facts - that God should seek to save the world by Jesus of Nazareth, Who was supposed unable to save himself Matthew 27:40-43; and that he should expect to save people by the gospel, by its being preached by people who were without learning, eloquence, wealth, fame, or power. The instruments were feeble; and people judged that this was owing to the weakness or lack of power in the God who appointed them.
Is stronger than men - Is able to accomplish more than the utmost might of man. The feeblest agency that God puts forth - so feeble as to be esteemed weakness - is able to effect more than the utmost might of man. The apostle here refers particularly to the work of redemption; but it is true everywhere. We may remark:
(1) That God often effects his mightiest plans by that which seems to men to be weak and even foolish. The most mighty revolutions arise often from the slightest causes; his most vast operations are often connected with very feeble means. The revolution of empires; the mighty effects of the pestilence; the advancement in the sciences, and arts, and the operations of nature, are often brought about by means apparently as little suited to accomplish the work as those which are employed in the plan of redemption.
(2) God is great. If his feeblest powers put forth, surpass the mightiest powers of man, how great must be his might. If the powers of man who rears works of art; who levels mountains and elevates vales; if the power which reared the pyramids, be as nothing when compared with the feeblest putting forth of divine power, how mighty must be his arm! How vast that strength which made, and which upholds the rolling worlds! How safe are his people in his hand! And how easy for him to crush all his foes in death!