+Mk 12: 35-37
As Jesus was teaching in the temple area he said, “How do the scribes claim that the Messiah is the son of David?
David himself, inspired by the holy Spirit, said: ‘The Lord said to my lord, “Sit at my right hand until I place your enemies under your feet.”‘
David himself calls him ‘lord’; so how is he his son?” (The) great crowd heard this with delight.
The New American Bible
The Catechism of the Catholic Church
“I BELIEVE IN ONE GOD”
200 These are the words with which the Niceno-Constantinopolitan Creed begins. The confession of God’s oneness, which has its roots in the divine revelation of the Old Covenant, is inseparable from the profession of God’s existence and is equally fundamental. God is unique; there is only one God: “The Christian faith confesses that God is one in nature, substance and essence.”
201 To Israel, his chosen, God revealed himself as the only One: “Hear, O Israel: The LORD our God is one LORD; and you shall love the LORD your God with all your heart, and with all your soul, and with all your might.” Through the prophets, God calls Israel and all nations to turn to him, the one and only God: “Turn to me and be saved, all the ends of the earth! For I am God, and there is no other.. . To me every knee shall bow, every tongue shall swear. ‘Only in the LORD, it shall be said of me, are righteousness and strength.'”
202 Jesus himself affirms that God is “the one Lord” whom you must love “with all your heart, and with all your soul, and with all your mind, and with all your strength”. At the same time Jesus gives us to understand that he himself is “the Lord”. To confess that Jesus is Lord is distinctive of Christian faith. This is not contrary to belief in the One God. Nor does believing in the Holy Spirit as “Lord and giver of life” introduce any division into the One God:
We firmly believe and confess without reservation that there is only one true God, eternal infinite (immensus) and unchangeable, incomprehensible, almighty and ineffable, the Father and the Son and the Holy Spirit; three persons indeed, but one essence, substance or nature entirely simple.
Ephrem the Syrian (Syriac: ܡܪܝ ܐܦܪܝܡ ܣܘܪܝܝܐ Mār Aprêm Sûryāyâ; Greek: Ἐφραίμ ὁ Σῦρος; Latin: Ephraem Syrus, also known as St. Ephraem (Ephrem, Ephraim); ca. 306 – 373) was a Syriac Christian deacon and a prolific Syriac-language hymnographer and theologian of the 4th century. He is especially beloved in the Syriac Orthodox Church, and counted as a Venerable Father (i.e., a sainted Monk) in Eastern Orthodoxy. His feast day is celebrated on 28 January and on the Saturday of the Venerable Fathers. He has been declared a Doctor of the Church in Roman Catholicism in 1920.
Ephrem wrote a wide variety of hymns, poems, and sermons in verse, as well as prose biblical exegesis. These were works of practical theology for the edification of the church in troubled times. So popular were his works, that, for centuries after his death, Christian authors wrote hundreds of pseudepigraphal works in his name. He has been called the most significant of all of the fathers of the Syriac-speaking church tradition.