Saint Anselm once asked the question, Cur Deus Homo? Why the God-man? The Franciscan thesis on this matter, systematically articulated by Bl. John Duns Scotus, is that the Incarnate Christ, the God-man would have taken place in salvific history with or without sin the sin of Adam. That is, the Incarnation is not contingent upon the fall of man in the Garden of Eden.
Saint Francis de Sales offered his support to the Franciscan thesis in his book, Treatise on the Love of God,
“All of God’s works are ordained to the salvation of men and angels; and the order of his providence is this, as far as, by attention to the Holy Scriptures and the doctrine of the Fathers, we are able to discover and our weakness permits us to describe it.
God knew from all eternity that he could make an innumerable multitude of creatures with divers perfections and qualities, to whom he might communicate himself, and considering that amongst all the different communications there was none so excellent as that of uniting himself to some created nature, in such sort that the creature might be engrafted and implanted in the divinity, and become one single person with it, his infinite goodness, which of itself and by itself tends towards communication, resolved and determined to communicate himself in this manner. So that, as eternally there is an essential communication in God by which the Father communicates all his infinite and indivisible divinity to the Son in producing him, and the Father and the Son together producing the Holy Ghost communicate to him also their own singular divinity; – so this sovereign sweetness was so perfectly communicated externally to a creature, that the created nature and the divinity, retaining each of them its own properties, were notwithstanding so united together that they were but one same person.
Now of all the creatures which that sovereign omnipotence could produce, he thought good to make choice of the same humanity which afterwards in effect was united to the person of God the Son; to which he destined that incomparable honor of personal union with his divine Majesty, to the end that for all eternity it might enjoy by excellence the treasures of his infinite glory. Then having selected for this happiness the sacred humanity of our Savior, the supreme providence decreed not to restrain his goodness to the only person of his well-beloved Son, but for his sake to pour it out upon divers other creatures, and out of the mass of that innumerable quantity of things which he could produce, he chose to create men and angels to accompany his Son, participate in his graces and glory, adore and praise him for ever. And inasmuch as he saw that he could in various manners form the humanity of this Son, while making him true man, as for example by creating him out of nothing, not only in regard of the soul but also in regard of the body; or again by forming the body of some previously existing matter as he did that of Adam and Eve, or by way of ordinary human birth, or finally be extraordinary birth from a woman without man, he determined that the work should be effected by the last way, and of all the women he might have chosen to this end he made choice of the most holy virgin Our Lady, through whom the Savior of our souls should not only be man, but the child of the human race.”
– Lucas G. Westman