The Christian world is now joyfully looking forward in time to Christmas: the celebration of the birth of our Lord and Savior Jesus Christ, the Word made flesh to dwell amongst us. Today we celebrate the second Sunday of Advent, our period of preparation for the birth of Christ. More specifically, today we Catholics light the Bethlehem Candle as a reminder in faith of the journey of the Blessed Virgin and Saint Joseph to Bethlehem.

We therefore are now in preparation for God’s presence among us. But if Christ is a person, born of Mary, is He truly a human person? And if so, does this not mean that in this sense of the Trinity that God is in fact composed of matter; that God is somehow material? The answer to this important question, if we examine the works of Aquinas, and also Ockham and Scotus, would be no! The Nestorian heresy, for example, held that Christ existed as two persons: the man as well as the Son of God; not as a unified person. For Aquinas, Christ’s human nature is a substance composed of a real body as well as an intellective soul.1 Further, the Council of Chalcedon “mandates that the Son be understood as simultaneously wholly immaterial and partially material.”2

Before the now famous Johannine proclamation that “the Word became flesh and lived among us, and we have seen his glory, the glory as of a father’s only son, full of grace and truth” (John 1:14), Saint Paul was proclaiming the dual humanity and divinity of Christ to those whom he converted to the faith. For example, in Galatians 4:4-5 Paul wrote that “when the fullness of time had come, God sent his Son, born of a woman, born under the law, in order to redeem those who were under the law, so that we might receive adoption as children.” In Romans 1:3-4 Paul tells us that Jesus “was descended from David according to the flesh and was declared to be Son of God with power according to the spirit of holiness by resurrection from the dead.” Also Saint Athanasius of Alexandria responded to Arius in the fourth century, in keeping with the promulgations of the Council of Nicea, for Christians to rightfully understand Christ: “one must see that he is at the same time the eternal Word and a human being. The imperfections displayed by Christ – hungering, thirsting, growing weary – are ‘things proper to this flesh’ that the Word took on; likewise, the perfections displayed by Christ – raising the dead, healing the sick – are ‘the proper works of the Logos.’”3

Circling back to Aquinas, whether God can be considered to be composed of matter, or “stuff” because of the humanity of Christ as the second Person of the Trinity does not require, as the Church Fathers and Church Councils mentioned above attest, a conclusion that Christ was not fully human as well as fully God. For Aquinas, “whatever matter is, it is in potency.”4 God is perfectly active and perfectly complete, which entails there is no potency in God. As such, “without any composition, there can be no distinction between God’s actions and his potential to act. God is what God does; there is no division within God that prevents God from doing what God wills. Since He excludes potency, God can be defined as pure action.”5

Perhaps this is best explicated by going back to the Creed promulgated by the Council of Nicea, which Catholics routinely profess at Holy Mass, and articulates that though Jesus was human, He was “begotten, not made, consubstantial with the father:”

I believe in one Lord Jesus Christ,

the Only Begotten Son of God,

born of the Father before all ages.

God from God, Light from Light,

true God from true God,

begotten, not made, consubstantial with the Father...

The fact that Christ in our Catholic faith is one person (hypostasis) who possesses two natures (dyophyses), one fully divine and one fully human, in no way detracts from Aquinas’ conclusion that God is not composed of matter. In Chalcedon’s conclusion we have the definitive Christological language communicatio idiomatum (exchange of properties) that proves this to be the case: because of Christ’s hypostasis, His unity of person, both of the Lord’s attributes of the divine and human natures (dyophyses) are to be predicated on each other; as Jesus Christ is understood to be both fully God and fully human as one person, consubstantial with the Father. It is this Incarnation of the Lord for which we prepare ourselves this holy Advent season. Today we continue on our journeys to embrace with all our hearts, all our minds, and all our faith the coming of the Lord.