“Therefore. Of the nine times dio kai occurs in the NT, three are in Luke / Acts. It involves a certain causality; and Lyonett, ‘L’ Annonciation,’ 61:6, points out that this has embarrassed many orthodox theologians, since in pre-existence christology a conception by the Holy Spirit in Mary’s womb does not bring bring about the existence of God’s Son. Luke is seemingly unaware of such a christology; conception is causally related to divine sonship for him.”
(Raymond E. Brown, The Birth of The Messiah: A Commentary on the Infancy Narratives in the Gospels of Matthew and Luke, p. 291)
This is a trinitarian speaking, but this isn’t JAT speaking.
Why has it embarrassed many orthodox theologians?
They’re orthodox trinitarians; Luke isn’t. Luke’s theology isn’t their theology.
Luke is saying that God caused Jesus, the Son of God, to come into existence in the womb of the virgin.