Saint Louis de Montfort says that the true Slaves of Jesus through Mary will have a special devotion to the Incarnation (True Devotion , No. 243). Those who desire to be disciples of this great spiritual writer of the Church — an inspiration to so many other saints1 — would do well to consider what a devotion to the Incarnation entails.

At its most basic level, honoring the Incarnation is honoring the Blessed Trinity’s loving plan for redeeming mankind and for overshooting the mark in that respect by giving us “so great a redeemer” (Saint Augustine’s Exultet ). It is also honoring the central historical fact resulting from that plan: the Second Person of the Eternal Trinity taking flesh in our Lady’s womb, making Mary the “bridal chamber in which the Word espoused flesh unto Himself,” in the tender expression of Saint Proclus of Constantinople.

When we probe deeper, we see that the Church is the extension — in time and in space — of the Incarnation of the Word. This is why the Church is called the “Mystical Body of Christ.” What Jesus was by nature, we become by grace, because we are united to Him in the Mystical Body — first in Baptism and, most excellently, in the Eucharist. For this reason, we can say that the Incarnation is a mystery that continues in us. This is why Father d’Alzon, about whom we wrote recently , could say that his work as a priest and religious was to “help Jesus continue His Mystical Incarnation in the Church and in each of the members of the Church.”

This “Mystical Incarnation” is a rich patristic doctrine, the root of all sound Marian piety, the foundation of our moral life, and the flowering of the doctrine of the Eucharist.

Our Lord, whose delights are to be with the children of men, chose to be with man by becoming one of us. In so doing, He gave us the means by which to become what He is: divine . This is the deification , or divinization , of man spoken of by many of the Fathers of the Church. The Greeks and other Eastern Christians, who lay great stress on the doctrine, call it theosis . It is a concept found both in the East and the West.

In the traditional Roman liturgy, an antiphon for the Octave of Christmas expresses the teaching fittingly: “O admirable exchange! The Creator of the human race, taking upon Himself a body and a soul, has vouchsafed to be born of a Virgin, and, appearing here below as man, has made us partakers of His Divinity .”

Saint Athanasius said it most powerfully in his On the Incarnation : “The Son of God became man, that we might become God.”

In his Summa Theologiae , Saint Thomas Aquinas quotes Saint Augustine in a similarly jolting turn of phrase: “The full participation of the Divinity . . . is the true bliss of man and end of human life; and this is bestowed upon us by Christ’s humanity, for Augustine says in a sermon: ‘God was made man, that man might be made God.'”

The Fathers of the East and West, and the medieval scholastics, too, all agree that men are deified by grace, and thus “made partakers of the divine nature,” as the first pope expressed it (2 Pet. 1:4).

In order not to get lost in an esoteric and unorthodox mysticism of the Buddhist or Hindu type — or the polytheism of the Mormon — we must ground this idea in the economy of the Incarnation, of the Church, and of the sacraments. The saints whom we just cited did that, and so does the Traditional Roman Rite Mass. At the Offertory, while mixing a few drops of water with the wine, the priest prays: “Grant that by the Mystery of this water and wine, we may be made partakers of His divinity , who vouchsafed to be made partaker of our humanity, Jesus Christ, our Lord, Thy Son. . . .” Appropriately, the Church presents us with the mystery of our deification when its ultimate earthly expression is about to occur — in the consecration and communion of Holy Mass.

It is supremely in this great Sacrament that we become one with Christ. This fact led Saint Augustine to give full expression to his sacred eloquence in a sermon on the Eucharist: “Be what you see and receive what you are,” he told his flock. We might express the idea less tersely: Our partaking in the sacramental Body of Christ forms us into the Mystical Body of Christ and into that union with the Incarnate God that makes each of us divine.

In rhapsodic Byzantine fashion, Saint John Damascene expressed the same truth under the figure of fire: “Let us draw near to it with an ardent desire . . . let us receive the body of the Crucified One . . . that we may be inflamed and deified by the participation in the divine fire.”

The men whose thoughts we have read were men of the Church . Their thinking is firmly rooted in the mystery of the Church, whose role in our sanctification is not merely accidental but essential. For it is this union with Christ in the Mystical Body — which is the Catholic Church — that makes us part of the one man who will ascend into heaven: “And no man hath ascended into heaven, but he that descended from heaven, the Son of man who is in heaven” (John 3:13 ). Only in participating in Christ’s Incarnation will we participate in His glorious Ascension into Heaven. In short, our union with Christ through the Church is not merely a good thing; it is a necessary thing in order that we might achieve the one end for which God created us. After defining “One indeed is the universal Church of the faithful, outside which no one at all is saved,” Pope Innocent III speaks of the Mystical Incarnation and the Eucharist: “The bread [is changed] into His body by the divine power of transubstantiation, and the wine into the blood, so that to accomplish the mystery of unity we ourselves receive from His [nature] what He Himself received from ours .”

The Mystical Incarnation is the foundation of our moral life. If we are to be true to our new nature received in baptism, we must live as other Christs, making His virtues ours, and burning up sin and vice in that “fire” of which Saint John Damascene made mention. The Imitation of Christ is not only the name of a spiritual bestseller, it is a way of life for those in whom Christ lives. “And I live, now not I; but Christ liveth in me” (Gal. 2:20).

Finally, the Mystical Incarnation also embodies our perfection; for this deification, which is begun in us in baptism, increases in us in the measure that sanctifying grace and divine charity do. The Incarnate Word grows in us. This is why we pray, in the words of Saint Louis de Montfort’s prayer of total consecration, “to come to the fullness of His age on earth and of His glory in heaven.”

The “Mystical Incarnation” is a reality that embraces the Trinity, the Immaculate Heart, the Church, the Mass, and the Sacraments. It is dogma and it is piety. It is sacred history and the sanctified present. And may it be to all of us more than mere words.

The prayer of the “Mystical Incarnation” par excellence is “Jesus Living in Mary,” a product of the French School of spirituality that formed Saint Louis de Montfort: “O Jesus, living in Mary, come and live in Thy servants, in the spirit of Thy holiness, in the fullness of Thy might, in the truth of Thy virtues, in the perfection of Thy ways, in the communion of Thy mysteries. Subdue every hostile power in Thy spirit for the glory of the Father. Amen.”

1 Among the saints to practice “holy slavery” as elucidated by Saint Louis were: St. Maximilian Maria Kolbe, Pope Saint Pius X, and Saint Katharine Drexel.