As for most of the French School of Spirituality, the doctrine of the Incarnation holds a central place in the thinking of St. Louis Marie de Montfort. But he does not approach this doctrine simply from the angle of speculative theology, but rather he meditates, full of wonderment and love, on the mystery of Jesus, Eternal and Incarnate Wisdom of God.
For St. Louis Marie, the Incarnation of the Second Person of the Trinity, the Son, in the man Jesus Christ, is a manifestation of "the prodigious excess of the love of God" for men and women (LEW 108). But it is also the beginning of our salvation, since in the Incarnation, God becomes man, so as to enable man to share once again in the Godhead, to become once again "the living image of the Godhead" (LEW 37). It is the beginning of the vast act of giving birth to the new humanity in Jesus Christ. And as Mary, by God's choice, had an essential role to play in the giving of his individual humanity to the Word of God, so, in Montfort's thought, she has an essential role in bringing forth the whole Christ, Head and members (cf. TD 17, 32).
St. Louis Marie also sees in the Incarnation, the supreme example of the attitude towards Mary that all Christians ought to make their own, namely one of filial "dependence" on her and obedience to her. Not only was this the attitude which Jesus Christ chose to have towards her by becoming her son, an example which we ought to imitate; but it is the natural response to the fact that we too, through the Incarnation, are her children. This is the foundation of the form of devotion (called sometimes "Holy Slavery") to Mary which he recommends as being the best way to achieve union with Christ: "total consecration to Jesus Christ through Mary" as her children and servants. St. Louis Marie, for this reason, sees the mystery of the Incarnation as the "mystery proper" to this perfect practice of devotion to Mary:
"Time does not permit me to linger here and elaborate on the perfections and wonders of the mystery of Jesus living and reigning in Mary, or the Incarnation of the Word. I shall confine myself to the following brief remarks. The Incarnation is the first mystery of Jesus Christ; it is the most hidden; and it is the most exalted and the least known. It was in this mystery that Jesus, in the womb of Mary and with her co-operation, chose all the elect. For this reason the saints called her womb, the throne-room of God's mysteries. It was in this mystery that Jesus anticipated all subsequent mysteries of his life by his willing acceptance of them. Consequently, this mystery is a summary of all his mysteries since it contains the intention and the grace of them all. Lastly, this mystery is the seat of the mercy, the liberality, and the glory of God" (TD 248).
So, for St. Louis Marie, the Incarnation is not only an essential mystery; it is the fundamental mystery of the economy of salvation, and the one at the heart of his spirituality.
The Second Vatican Council speaks also of the Incarnation as the "supreme mystery" which will bring us, by our meditation on it, to become ever increasingly like Jesus Christ (Lumen Gentium 65). And Pope John Paul II, in his encyclical Redemptoris Mater, follows fairly closely Montfort's way of approaching the mystery of the Incarnation. It is also a mystery which underlines the sense of the greatness of humanity, because adopted by God: a concept which could help us today in our struggle to counteract the flouting of the rights of the weakest members of human society. St. Louis Marie's insistence on the Incarnation is therefore highly relevant today.