Summary: 1) The Cause (1 Corinthians 3:1–3a), 2) The Symptoms (1 Corinthians 3:3b–4), and 3) The Cure (1 Corinthians 3:5-9) for division.
When Companies struggle with human or mechanical processes, they hire experts which come into and identify faulty processes. Often those who engage in a task every day, become blind to the problems. They often fail to see the pitfalls before them.
The Corinthian believers had an especially hard struggle against the world and the flesh, a struggle which they seldom won. They would not break with the world or break with the flesh and were continually succumbing to both. Consequently they fell into one serious sin after another. Almost all of this epistle has to do with identifying and correcting those sins.
Our ultimate triumph over the world and the flesh is certain, but our continued struggle with them in this life is also certain. We will win the ultimate battle, but can lose a lot of skirmishes along the way. How then can we identify the pitfalls that are before us and avoid them? Human wisdom will appeal to our flesh which will blind us to the pitfalls before us.
From 1:18 through 2:16 Paul points out that the Corinthians were divided because of worldliness, because of their continued love for human wisdom. In 3:1–9 the apostle shows them that they also were divided because of the flesh, because of their continued yielding to the evil in their humanness. Using the analogies of Milk and Meat for division, he shows 1) The Cause (1 Corinthians 3:1–3a), 2) The Symptoms (1 Corinthians 3:3b–4), and 3) The Cure (1 Corinthians 3:5-9) for division.
1) The Cause of Division: the Flesh (1 Corinthians 3:1–3a)
1 Corinthians 3:1-3 [3:1]But I, brothers, could not address you as spiritual people, but as people of the flesh, as infants in Christ. I fed you with milk, not solid food, for you were not ready for it. And even now you are not yet ready, for you are still of the flesh. (For while there is jealousy and strife among you, are you not of the flesh and behaving only in a human way?) (ESV)
The cause of division in the church was more than an external, worldly influence. It was also internal, fleshly. The Corinthians had succumbed to the pressures of the world, but they were also succumbing to the pressures and enticements of their own flesh.
Before Paul chastises them for their immature sinfulness, he reminds them again that he is speaking to them as brothers/brethren, as fellow believers. The use of the vocative (“brothers [and sisters]”; see 1:10 and the second person plural pronouns throughout make it clear that he is not addressing a faction within the congregation, but the church as a whole. Brothers/brethren is a term of recognition and of love. He did not try to diminish the seriousness of their sins, but he did try to diminish or prevent any discouragement that his rebuke might otherwise have caused. He stood with them as a brother. Although, not all may be guilty, but all are defiled by the actions of the many (Fee, G. D. (1987). The First Epistle to the Corinthians (p. 123). Grand Rapids, MI: Wm. B. Eerdmans Publishing Co.).