Summary by Chapter
Paul argues against divisions and sectarianism. In arguing against division, he also argues against loyalty to anyone other than Christ. To that extent, he is grateful that he did not baptize many of them, as to be a cause for division, as many were identifying themselves into subsets of the Christian body by the one who baptized them.
Paul did not preach in a way that would reduce the effect of the cross of Christ (v 17), meaning he did not seek to draw attention to his style of preaching, but rather the content which would bring glory to Jesus. He goes on to talk about how the message that he preached (which brought glory to God), was one that was foolish to the world. And God was pleased that what the world thought was foolish, it would be a message that would save those whom God wanted. The world did not know God because knowing God required believing in things that the world thought (and still think) were foolish.
These Christians could look in their lives and understand that they were not the mighty and noble of the world, yet they were called (approved) by God. With this in mind, they could understand that their lives are proof that God uses foolish things (to the world) to shame the wise (of the world).
12-13 12 Now I say this, that each of you says, “I am of Paul,” or “I am of Apollos,” or “I am of Cephas,” or “I am of Christ.” 13 Is Christ divided? Was Paul crucified for you? Or were you baptized in the name of Paul?
18 18 For the message of the cross is foolishness to those who are perishing, but to us who are being saved it is the power of God
21 21 For since, in the wisdom of God, the world through wisdom did not know God, it pleased God through the foolishness of the message preached to save those who believe.
25 25 Because the foolishness of God is wiser than men, and the weakness of God is stronger than men.
27 27 But God has chosen the foolish things of the world to put to shame the wise, and God has chosen the weak things of the world to put to shame the things which are mighty