Psalm 110:1, “YAHWEH (the Divine Name appears) said to my Lord (adon means a human lord), sit at my right hand until I make your enemies the footstool of your feet.”
The text does not say, “Yahweh said to my Yahweh,” nor “Yahweh said to my Adonai” which would mean Yahweh God spoke to another person called Yahweh God. The text states that only One Yahweh God Person spoke to only one “adon” person as a human Lord. Hence, One Yahweh Person spoke to one human son person rather than One Yahweh Person speaking to another alleged Yahweh Person.
If Jesus had eternally existed as an alleged God the Son beside the Father throughout eternity past, then why did the Father say to the son, “sit at my right hand” if he was already at the Father's right hand to begin with? Trinitarian apologists often cite John 17:5 to allege that a God the Son shared divine glory at his Father’s side as a coequally distinct Yahweh God Person before his virgin conception and birth. Yet if the Son literally shared glory at his Father’s side before the foundation of the world, then the Father would not have prophetically spoken to His Son saying, “Sit at my right hand” during the Old Testament time period if he was already at his Father’s’ right hand to begin with.
Peter cited Psalm 110:1 in Acts 2:34-36 to show that a post incarnational Jesus would ascend into heaven as a human son to fulfil this prophecy. “For it was not David who ASCENDED INTO HEAVEN, but he himself says: “THE LORD (YHWH) SAID TO MY Lord (Adon), sit at my right hand, until I make your enemies a footstool for your feet. Therefore let all the house of Israel know for certain that God has MADE him [Greek verb poieó (poy-eh'-o) “Make, Manufacture, Construct, or Cause”] both Lord and Christ-- this Jesus whom you crucified”. Notice that God made Jesus “both Lord [kurios (koo'-ree-os) “Lord, master”] and Christ”. Thus, Acts 2:34-36 proves that Jesus was not always “both Lord and Christ” before God “made him both Lord and Christ”. Wherefore, just as 1 Tim. 2:5 says that there is only “One God (the Father) and one mediator between God and men, the man Christ Jesus,” so Psalm 110:1 says that there is only One Yahweh (the Father) and one human Lord (the son) who was “made both Lord and Christ” by the Father.