Let’s look at the other readings first. The Gospel was about “the best part” which was essentially being with Jesus. The psalm was about living in the presence of the Lord. The Old Testament reading represented inviting in the Holy Trinity (traditionally, the three angels are said to represent the Trinity).
So, we see the whole theme is living in union with God, inviting Him into our presence.
St. Paul’s letter, in regards to this theme, is that one of the greatest glories, if not the greatest glory, of the Gospel, is the mystery that Christ dwells within Christians and we in Him. He and the Church are inseparable, because we are His Body. Therefore, St. Paul exhorts us to bring this mystery and glory and share it with all men.
To live in the Church, is to live in the presence of Christ, to choose the best part.
Anyway, that was my take
