Albert Barnes Commentary 1 Corinthians 1:21

"For seeing that in the wisdom of God the world through its wisdom knew not God, it was God`s good pleasure through the foolishness of the preaching to save them that believe." — 1 Corinthians 1:21 (ASV)

For after that. epeidh. Since; or seeing that it is true that the world by wisdom did not know God. After all the experience of the world, it was ascertained that men would never by their own wisdom come to the true knowledge of God, and it pleased him to devise another plan for salvation.

In the wisdom of God. This phrase is open to two interpretations.

1. The first makes it refer to "the wisdom of God" shown in the works of Creation—the demonstration of his existence and attributes found there. According to this view, the apostle means that the world, by a survey of the works of God, did not know him; or, notwithstanding those works, was in deep darkness. This interpretation is adopted by most commentators—by Lightfoot, Rosenmuller, Grotius, Calvin, etc. According to this interpretation, the word en (in) is to be translated by, or through.
2. A second interpretation makes it refer to the wise arrangement or government of God, by which this was permitted: "For when, by the wise arrangement or government of God, after a full and thorough trial of the native, unaided powers of man, it was ascertained that the true knowledge of God would not be arrived at by man, it pleased him," etc. This appears to be the correct interpretation, because it is the most obvious one and because it suits the connection best. It is, according to this, a reason why God introduced a new method of saving men. This may be said to have been accomplished by a plan of God, which was wise, because:
   1. It was desirable that the powers of man should be fully tried before the new plan was introduced, to show that it was not dependent on human wisdom, that it was not originated by man, and that there was really a need for such an interposition.
   2. Because sufficient time had been provided to make the experiment. An opportunity had been given for four thousand years, and still it had failed.
   3. Because the experiment had been made in the most favourable circumstances. The human faculties had had time to ripen and expand; one generation had had an opportunity of profiting by the observation of its predecessor; and the most mighty minds had been brought to bear on the subject. If the sages of the East and the profound philosophers of the West had not been able to come to the true knowledge of God, it was in vain to hope that more profound minds could be brought to bear on it, or that more careful investigation would be bestowed on it. The experiment had been fairly made, and the result was before the world. (See Barnes' commentary on Romans 1:1)

The world. The people of the world; particularly the philosophers of the world.

By wisdom. By their own wisdom, or by the united investigations of the works of nature.

Knew not God. They did not obtain a true knowledge of him. Some denied his existence; some represented him under the false and abominable forms of idol worship; some ascribed to him horrid attributes. All showed that they had no true acquaintance with a God of purity, with a God who could pardon sin, or whose worship conduced to holiness of life. (See Barnes' commentary on Romans 1:1)

It pleased God. God was disposed, or well-pleased. The plan of salvation originated in his good pleasure and was such as his wisdom approved. God chose this plan, so unlike all the plans of men.

By the foolishness of preaching. Not "by foolish preaching," but by the preaching of the cross, which was regarded as foolish and absurd by the people of the world. The plan is wise, but it has been esteemed by the mass of people, and was particularly so esteemed by the Greek philosophers, to be egregiously foolish and ridiculous. (See Barnes' commentary on 1 Corinthians 1:18)

To save them that believe. That is, those who believe in the Lord Jesus Christ. (See Barnes' commentary on Mark 16:16)

This was the peculiarity and essence of the plan of God; and this has appeared to the mass of people to be a plan devoid of wisdom and unworthy of God. The preaching of the cross, which is thus esteemed foolishness, is made the means of saving them because it sets forth God's only plan of mercy and states the way in which lost sinners may become reconciled to God.