“Adonai” is Hebrew for “my LORD.” Out of reverence for God, devout Jews will not speak the name revealed to Moses so long ago. Adonai is the endearing term used to recognize the God who is creator of all that is seen and unseen, redeemer of the world, and true God.
The second antiphon in the Octave of Christmas progresses the Church from creation, to the familiar story of God making his name known to his people. The LORD brings Moses into relationship by revealing his name and imparting his law (Ex. 20:1-20) upon the people Israel, whom God chose to live in covenant with him.
Through Holy Scripture, the Church is reminded how God delivered the children of Israel from bondage under pharaoh. This deliverance is a foreshadowing of the redemption from sin which comes through Jesus Christ. The image of God’s arm outstretched in power to save his chosen people brings to mind the later scene of Jesus with his arms outstretched for us on the cross. Through the death and resurrection of his Son, Adonai brings into relationship with him, all who receive his grace through the covenant of Holy Baptism and believe Christ is Lord of all.
And so in Advent the church sings:
O come, O come O LORD of might,
as to your tribes on Sinai’s height.
In ancient times you gave the law
in cloud and majesty and awe. Rejoice!
O Come, O Come Emmanuel v. 3 Traditional