I am referring to the following clause ( clause III) in "The Anathematisms of the Emperor Justinian Against Origen"
If anyone says or thinks that the soul of the Lord pre-existed and was united with God the Word before the Incarnation and Conception of the Virgin, let him be anathema.
This is inconsistent with an important pillar of orthodox Christianity ( not to be confused with eastern orthodoxy) doctrines: the doctrine of Trinity, which states that the Father, the Son and the Holy Spirit always exist.
All three divine Persons—Father, Son and Holy Spirit—share the one being of God. The Trinity doctrine explains that Jesus was not created sometime prior to his incarnation, but existed eternally as God.
Obviously these two can't be both right, so, how can "The Anathematisms of the Emperor Justinian Against Origen" and the Trinity doctrine be reconciled from orthodox Christianity point of view? Or the view expressed in "he Anathematisms of the Emperor Justinian Against Origen" is never a part of Christianity teaching?