The English word “LORD,” in all caps, is how we translate the Hebrew ”YHWH”, the four holy letters that the Jewish people don’t actually pronounce. They will sometimes say “HaShem” literally “the Name” but will avoid saying YHWH. So, the story continues,So, Moses cut two tables of stone like the first; and he rose early in the morning and went up on Mount Sinai, as the LORD had commanded him, and took in his hand two tables of stone. And the LORD descended in the cloud and stood with him there and proclaimed the name of the LORD. Ex. 34:4
So, consider the imagery: The Lord descended in the cloud, think of the experience of the Holy Spirit. The Lord stood with him, as Christ stood with us. The “Lord” is the principal title for Jesus, for the Son, used by his disciples. In the ancient Christian tradition, St. Justin Martyr and St. Irenaeus, appearances of God, like the three men who come to Abraham in Genesis 18-19, the Church Fathers taught that was the Son, coming to humanity in a way that prefigured the Incarnation. So, in the story of Moses, the cloud symbolizes the Spirit, and the Lord is the image of the Son. The Catechism of the Catholic Church, paragraph 707, teaches, thatThe LORD passed before him, and proclaimed, "The LORD, the LORD, a God merciful and gracious, slow to anger, and abounding in steadfast love and faithfulness.” And Moses made haste to bow his head toward the earth and worshiped. And he said, "If now I have found favor in thy sight, O Lord, let the Lord, I pray thee, go in the midst of us, although it is a stiff- necked people; and pardon our iniquity and our sin, and take us for thy inheritance." Ex. 34
The theophany recounted in the reading from Exodus, reflects the tradition of seeing theophanies as a sign of the mystery of the Trinity that will be revealed in the New Testament.Theophanies (manifestations of God) light up the way of the promise, from the patriarchs to Moses and from Joshua to the visions that inaugurated the missions of the great prophets. Christian tradition has always recognized that God's Word allowed himself to be seen and heard in these theophanies, in which the cloud of the Holy Spirit both revealed him and concealed him in its shadow.
So, Paul is a Jew, a monotheist, who would have prayed, “Hear, O Israel: The Lord our God is one Lord” (Deuteronomy 6 ). In the next verse St. Paul saysFinally, brethren, farewell. Mend your ways, heed my appeal, agree with one another, live in peace, and the God of love and peace will be with you. Greet one another with a holy kiss. All the saints greet you. 2 Cor. 3:11-13
St. Paul is explicitly Trinitarian. It is still the greeting we use to begin the mass.The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all. 2 Cor. 3:14
So, in the Greek it literally says “God gave his only begotten Son, so that whoever believes in him might not perish.” One reason that is important is because it sets Jesus out as a unique kind of son. We are ‘sons of God’, by adoption through baptism. Rom. 8, Gal. 3. The Lord is the “only begotten Son of God.” Jesus is God’s Son in a completely unique way; light from light, true God from true God.For God so loved the world that he gave his only Son, that whoever believes in him should not perish but have eternal life. For God sent the Son into the world, not to condemn the world, but that the world might be saved through him. He who believes in him is not condemned; he who does not believe is condemned already, because he has not believed in the name of the only Son of God. John 3:16