Paul struck gold in 1 Corinthians 10

It is not easy to summarize the whole of chapter 10 under one theme. Warning against idolatry probably can loosely connect the whole chapter.
It began with a commentary on the wilderness experience of Israelites. Most of the first generation Israelites who left Egypt perished in the wilderness and Paul saw this as a warning for his contemporaries.
Now these things are warnings for us, not to desire evil as they did. (1 Corinthians 10:6)
Truly, the stories written down in the Bible tell us of people's encounters with God, their successes and failures; their ascents and downfalls. Failures and downfalls are usually attributed by Biblical authors to idolatry which had been the major concern for Paul because early Christians lived in a pagan world whose life was saturated with it. Temptation was everywhere.
No temptation has overtaken you that is not common to man. God is faithful, and he will not let you be tempted beyond your strength, but with the temptation will also provide the way of escape, that you may be able to endure it (1 Corinthians 10:13).
It is very encouraging indeed. God will not let us be tempted beyond our strength. Probably this verse is the origin of another popular Christian aphorism: God is faithful. He will not give us a cross too heavy for us to bear/carry.
In his commentary on the wilderness experience, Paul struck gold! He identified Jesus as the Rock from which the Israelites drank!
and all ate the same supernatural food
and all drank the same supernatural drink. For they drank from the supernatural Rock which followed them, and the Rock was Christ (1 Corinthians 10:3-4).
This is a spirituality and theology gem. Early Christians must have been very anxious to position themselves as the true Israel. They needed to trace their root back to the Old Testament and reinterpret it in their favour. Here, Paul and John shared the share vision --- that Jesus is the running water and flows to eternity. John wrote several decades later and enjoyed a time advantage. His theology would be more mature. He was able to relate the wound pierced on Jesus' side as the source of living water flowing to eternity. Jesus is the Rock.
However, Paul did not have the time advantage. He died early and was only able to develop the theology of the Mystic Body of Christ, whereas John was able to develop the theology of manna, the bread from heaven.
In this epistle, his discussion of the Holy Communion focused on oneness with Christ, forming the Mystical Body. His target was to refute idolatry.
You cannot drink the cup of the Lord and the cup of demons. You cannot partake of the table of the Lord and the table of demons (1 Corinthians 10:21).
Paul was too eager to fight against idolatry. He missed the chance to develop a spirituality of the bread of life, like what John had done. Of course, God has His deployment plan.
Nevertheless, Paul left us very good aphorisms. For example:
"All things are lawful," but not all things are helpful. "All things are lawful," but not all things build up (1 Corinthians 10:23, 6:12).
Let no one seek his own good, but the good of his neighbor (1 Corinthians 10:24).
So, whether you eat or drink, or whatever you do, do all to the glory of God (1 Corinthians 10:31).
Before I leave, let me put down some LXX references. This time in chapter 10, Paul simply copied from LXX. As for Psalm, it is understandable. But he copied even the Torah section of LXX. As a Pharisee, Paul was very familiar with the Torah. In other epistles or even other parts of this epistle, Paul translated the Torah himself into Greek. But not for this time.
ἐκάθισεν ὁ λαὸς φαγεῖν καὶ πεῖν καὶ ἀνέστησαν παίζειν.
The people sat down to eat and drink and rose up to dance. (1 Corinthians 10:7b)
ἐκάθισεν ὁ λαὸς φαγεῖν καὶ πιεῖν καὶ ἀνέστησαν παίζειν. (Exodus 32:6b)

τοῦ κυρίου γὰρ ἡ γῆ καὶ τὸ πλήρωμα αὐτῆς.
the earth is the Lord's, and everything in it. (1 Corinthians 10:26)
Τοῦ κυρίου ἡ γῆ καὶ τὸ πλήρωμα αὐτῆς, (Psalm 23:1b LXX, Psalm 24:1b MT)

My dear Advocate, it has been a pleasure to read the first epistle to the Corinthians. Let us learn from Paul and from his reasoning. His deep love for the Israelites is admirable. Very often, familiarity breeds contempt. In Hong Kong, we are easily disgusted with what the Mainland Chinese do. I pray for the baby victims of the recent baby-formula scandal. May they recover and grow healthily. Amen.