In speaking of Christ, the Creed uses two words that we are not used to: “begotten” and “consubstantial.” Although unfamiliar, these terms can help us appreciate who Jesus is.
The Father eternally begets the Son, which means that for all eternity the Father gives his being to the Son. To put it differently, there is never a “moment” in which the Son doesn’t exist. He is not created, but eternally comes from the Father. The relationship that God has with his creation, therefore, is rooted more firmly and eternally in his relationship with his Son. This reveals to us that God is an eternal relationship. The Father exists for the Son, and the Son for the Father, through the bond of the Holy Spirit. Thus when God creates, all creation is rooted in this relationship of God.
The fact that the Son is eternally begotten of the Father is confirmed by the term “consubstantial.” The word “con” is rooted in the Latin for “with,” and substance refers to what makes up an entity. Consubstantial, as used in the Creed, refers to the Son as “with the same substance” of the Father. Substance is the very being of God. Whatever is of God is completely and totally in the Son as it is in the Father and the Holy Spirit.
This Son of the Father is the one who takes on human flesh so that he may come to rescue humanity from the bonds of sin and death. He takes on a humanity that is totally ours from his mother Mary. By entering into the world, the Son comes to repair what is broken, namely, that relationship with the Father. He comes to lift up creation once again into proper relationship with God, but this time with something new: to have by adoption what he has by nature: to share the substance, the very life of God.