In his "Disputation between a Christian and a Saracen," Damascus, responding to a "Saracen" (Muslim) wrote the following which is of Mariological importance:
Section 2c: The communication
of the Word to men: The Incarnation
And if a Saracen asks
you, “How did God descend into the womb of a woman,” say to him, “Let us use
your Scripture and my Scripture. Your Scripture says that God purified (προεκαθηρεν) the Virgin Mary
above all other women and the Spirit of God and the Word descended into her . . .” (Daniel J.
Janoski, John of Damascus First Apologist to the Muslims: The Trinity and
Christian Apologetics in the Early Islamic Period [Eugene, Oreg.: Pickwick
Publications, 2016], 274)
This refers to Qur’an 3:42, “Behold the
angels said: O Mary Allah hath chosen thee and purified thee—chosen thee above
the women of all nations.”
While I think his
arguments about Oration 38 from Gregory Nazianzen does not hold up, I think
Christiaan Kaapes does a good job at showing that John of Damascus did hold to
a "proto-Immaculate Conception" understanding of the pre-purification
of Mary in his writings. See his "Immaculate
Conception: Why Thomas Aquinas Denied, While Duns Scotus, Gregory Palamas, and
Mark Eugenicus Professed Absolute Immaculate Existence of Mary."
