This year I have been doing a systematic study of 1 Corinthians. I do
about a verse a day, keeping a notebook of my thoughts and questions. I
am currently in chapter 4 verses 1-9. I am stuck and stumped.

Every commentary I read says Paul is defensive. Why? Why is he defensive? Why does he feel the need to defend himself?

1 Corinthians 4 (New American Standard Bible)

1 Corinthians 4

Servants of Christ

 ¹Let a man regard us in this manner, as ^(A)servants of Christ and ^(B)stewards of ^(C)the mysteries of God.

 ²In this case, moreover, it is required of stewards that one be found trustworthy.

 ³But to me it is a very small thing that I may be examined by you, or by any human court; in fact, I do not even examine myself.

 ⁴For I ^(D)am conscious of nothing against myself, yet I am not by this ^(E)acquitted; but the one who examines me is the Lord.

 ⁵Therefore ^(F)do not go on passing judgment before ^[a]the time, but wait ^(G)until the Lord comes who will both ^(H)bring to light the things hidden in the darkness and disclose the motives of men’s hearts; and then each man’s ^(I)praise will come to him from God.

 ⁶Now
these things, brethren, I have figuratively applied to myself and
Apollos for your sakes, so that in us you may learn not to exceed ^(J)what is written, so that no one of you will ^(K)become arrogant ^(L)in behalf of one against the other.

 ⁷For who regards you as superior? ^(M)What do you have that you did not receive? And if you did receive it, why do you boast as if you had not received it?

 ⁸You are ^(N)already
filled, you have already become rich, you have become kings without us;
and indeed, I wish that you had become kings so that we also might
reign with you.

 ⁹For, I think, God has exhibited us apostles last of all, as men ^(O)condemned to death; because we ^(P)have become a spectacle to the world, both to angels and to men.