Our starting-point must be the fact that God cannot be named... no mind has yet contained or language embraced God's substance in its fullness. No, we use facts connected with Him to outline qualities that correspond with Him, collecting a faint and feeble mental image from various quarters. Our noblest theologian is not one who has discovered the whole - our earthly shackles do not permit us the whole - but one whose mental image is by comparison fuller, who has gathered in his mind a richer picture, outline, or whatever we call it, of the truth.
Gregory of NazianzusMore Gregory of Nazianzus quotes
If anyone does not believe that Holy Mary is the Mother of God, he is severed from the Godhead. If anyone should assert that He passed through the Virgin as through a channel, and was not at once divinely and humanly formed in her (divinely, because without the intervention of a man; humanly, because in accordance with the laws of gestation), he is in like manner godless.
Gregory of Nazianzus