The problem with the Corinthians is highlighted here: instead of being spiritual, they are still “fleshy” (3:1). Additional phrase, “infants in Christ” give us an insight that there is also a process of growth in faith: from an infant to a mature person (see Heb 5:11–14; John 16:12).
What does Paul mean by “milk” can be perhaps drawn from Heb 6:1. “Milk” could refer to the kerygma - the main content of the message of the Gospel. It should follow by catechetical teaching to deepen their faith.
The infancy state of the community is revealed in their “envy and strife” (3:3). These two are mentioned in Gal 5:20 with an indication that those who commit such things will not inherit the Kingdom of God (Gal 5:21, see also Rom 13:13; 2 Cor 12:20).
Four groups were mentioned in 1:12, now only two - perhaps the main groups: one on the side of Paul, the other on the side of Apollos (see Acts 18:24–28).
Apollos was from Alexandria - the famous Egyptian city with a strong Jewish community - (according to the tradition LXX was published there). The city had also huge library and it was a center of high learning. Luke describes him as “man of words - eloquent” and “being powerful in Scriptures” (Acts 18:24). Thus, he had to be well-educated in Greek philosophy and Jewish tradition.
The friends of Paul - Aquila and Priscilla - introduced him to the full message of the Gospel (he had just rudimentary understanding of the Gospel. Then, he moved to Corinth. It was his oratorical skills that made him famous but it also contributed to the division within the community of Corinth.
Verse 3:5 - ministers or servants - diakonoi. The word means serving the tables - the ministry of charity (Acts 6:1), and preaching the Gospel (2 Cor 11:23, see also Col 1:24–25 - diakonos of the Church).
The ministry of apostles compared to that of planting and watering. Paul established that church in Corinth - planted it; Apollos later on continued to deepen their faith - catechesis - “watering”. But, both are the servants of God, and it is God that matters, not the servants (see Matt 13:3–9).
Yes, it is through the apostles that the Corinthians believed, but faith is a direct gift from the Lord.
The point is: both - Paul and Apollos - work on the same project - God’s project of bringing nations to the obedience of faith.
Apostles - “fellow-workers with God” - synergoi (Greek). From here, we have the word synergy - combined action or operation.
Corinthians - “cultivated land of God” and “God’s building”.
3:10–15
Paul presents himself as a “wise architect / master builder”. It is he who places the fundament of the building - the most important part of any building - and there can only be one fundament (see Matt 7:24–27).
“Jesus Christ” as fundament - the Gospel - and not Moses, the Law or Greek philosophy.
By now we know that:
1. The one who came out with the project is God;
2. The fundament is Jesus Christ;
3. The master builder is Paul.
Now, it is upon to others to build further.
Note. From here, we can glimpse into the evangelizing method of Paul. Based on it, we can draw conclusion that Paul focused on laying the fundament - the first proclamation of the Gospel (kerygma). Any further catechesis, he seemed to leave to others. In this way, he could move so fast from one place to another. When he judged that the foundation was laid, he left the rest of the work to other ‘ministers’ - like Apollos.
The metaphor of building further includes six materials:
The quality of the work - the entire building - will be manifested on “the day”. It is probably a reference to the day of the Lord understood as judgement (Mal 3:2; 1 Thess 5:2–3). It will be tested by fire (Is 66:16; Mal 3:19; 2 Thess 1:8).
In the context of the text, verses 3:14–15 should refer to those ministers like Apollos, who build on Paul’s fundament - Jesus Christ. It would refer then to the shepherds of the community (1 Peter 5:1–4). Shepherd and the entire community will have to pass the tests of faith. It is unavoidable. But what would the outcome of this test? The risen Lord in Rev 3:18 advised the church in Laodicea - which failed His test of faith - to buy from the Lord “gold tried in fire”. Among the seven churches of the book of Revelation, this one was in the worst condition from the perspective of faith.
Traditional - since Origen (3rd century CE) - the text is seen as a proof of text for purgatory (see also 1 Peter 1:7). In the Bible, there is a destructive fire (Gen 19:24; Num 11:1) and the purifying fire (Num 31:23; Mark 9:49; 1 Peter 1:7). This purifying fire is seen as the fire of purgatory.
3:16–17
From the metaphor of building, Paul moves to a metaphor of a ‘finished product’ - the temple. Built on the foundation of Jesus Christ, the community is the holy temple of God. What is the proof? The presence of the Holy Spirit. (But see 1 Cor 6:19 - an individual as the temple of the Holy Spirit).
The word “phthereio” means: to corrupt, defile, destroy. In the opinion of the Jews, the temple was corrupted or “destroyed” when anyone defiled or in the slightest degree damaged anything in it (see 1 Maccabees 1:54.59; 4:36:55; Acts 21:28; Mark 11:15–18). In the New Testament in can mean to lead a Christian from that state of knowledge and holiness in which it ought to abide (1 Cor 15:33; 2 Cor 7:2) and even to corrupt the world (Rev 19:2).
3:18–23
Paul is back to his main theme: wisdom versus foolishness. The move from wisdom to foolishness indicates “repentance” - a change in the way one thinks. It is a move from worldly way of thinking to embracing the Christian way of thinking rooted in the Gospel. Paul again has in mind the folly of the Cross as the wisdom and power of God (1:18).
The two quotes come from Job 5:12 and Ps 94:11.
The conclusion comes in verses 3:21–22 and is a direct answer to 3:4. The “admirers/disciples” of Paul should not consider themselves better than the “admirers/disciples” of Apollos and vice verse.
There is a hierarchy here: from Corinthians to Christ, from Christ to God. In between, Paul indicates that Corinthians possess everything: world, life, death, things present, and things coming (see Rom 8:38–39).
Into the disorder of the community, Paul brings an order to hierarchy:
1. universe, human existence in this world and the future yet to come;
2. Those who preached the Gospel to the Corinthians;
3. The Corinthians themselves;
4. Christ;
5. God.
For a similar hierarchical order in this letter see also: 1 Cor 8:6, 11:3; 15:28.