Yesterday we looked at the Chalcedonian Creed, which consists of the orthodox statement affirming the biblical truth that Jesus is fully God and fully man. The key expression is summarized in the affirmation “one person, two natures.” In theological/doctrinal terms, this is what we are addressing when we discuss the hypostatic union (the Greek hypostasis means “being,” “substance,” “nature,” “essence,” or “person”).

The term Creed comes from the Latin credo, which means ‘I believe’. Creeds consist of statements of belief, explicit statements of truth that are confessed, both individually and corporately. But for every explicit statement of belief is an implicit statement of denial. For example, one of the early Christological confessions in the New Testament is that Jesus is God (Jn. 1:1, 18; 20:28; Acts 20:28; Rom. 9:5; Tit. 2:13; Heb. 1:8; 1 Jn. 5:20; 2 Pet. 1:1). When Christians explicitly affirm this truth, they are implicitly denying any statement that denies or undermines this truth. Though not stated, we deny the teaching of the Arians who claimed Jesus was not fully God, and today we implicitly deny the teaching of the Jehovah’s Witnesses who claim Jesus is a god.

This is reflected in the Chalcedonian Creed as well. It is important to note that this Creed attempted to address every Christological heresy that had affected the church up to that time. Robert Reymond (A New Systematic Theology of the Christian Faith [Nashville: Thomas Nelson Publishers, 1998], 608-609) helpfully makes explicit these implicit denials, which I have adapted and expanded.

1. Against the Docetists (Jesus only appeared to be human) it declared that the Lord Jesus Christ was perfect in manness, truly man, consubstantial with us (homoousion, not homoiousion, i.e. he is not of “like substance or being” with us, but he is “of the same substance” with us) according to manness, and born of Mary.
2. Against the Samosatian adoptionists (at some point, baptism, the human Jesus was adopted by the Father to become the Son) it insisted upon the personal subsistence of the Logos “begotten of the Father before the ages.”
3. Against the Sabellians (a form of modalism) it distinguished the Son from the Father both by the titles of “Father” and “Son” and by its reference to the Father having begotten the Son before all ages.
4. Against the Arians (Jesus was not eternal, but created, stated as “there was time when he was not”) it affirmed that the Lord Jesus Christ was perfect in deity, truly God, and consubstantial with the Father (homoousion, not homoiousion, i.e. he is not of “like substance or being” with the Father, but he is “of the same substance” with the Father). (An earlier version of this was known as Ebionism.)
5. Against the Apollinarians (one person of Christ had a human body but not a human mind and spirit which were of divine nature), who had reduced Jesus’ manness to a body and an “animal soul” (psyche alogos), it declared that Jesus had a “rational soul” (psyche logike), that is, a “spirit.”
6. Against the Nestorians (two separate persons in Christ, a human person and a divine person) it both described Mary as theotokos, i.e. the God-bearer (not Christotokos, i.e. the Christ bearer, emphasizing that Mary bore the man Jesus, undermining that she actually bore the God-man Jesus) not in order to exalt Mary in the slightest, but in order to affirm Jesus’ true deity and the fact of a real incarnation, and spoke throughout of one and the same Son and one person and one subsistence, not parted or divided into two persons and whose natures are in union without division and without separation.
7. Finally, against the Eutychians (Christ has one nature only, human nature was absorbed into the divine nature so a third kind of nature resulted), it confessed that in Christ were two natures without confusion and without change, the property of each nature being preserved and concurring in the one person.

As Evangelicals committed to the gospel of Jesus Christ, the faith once for all entrusted to the saints (Jude 3), and as those who are a part of the longer and larger Evangelical stream throughout the history of the church, we, like our Evangelical predecessors, affirm Chalcedonian Christology, as a statement that summarizes the Bible’s teaching about Jesus Christ. Here is the conclusion in Evangelical Convictions: A Theological Exposition of the Statement of Faith of the Evangelical Free Church of America (pp. 98-99):

Jesus Christ is thus one Person in whom two distinct natures are united.

Jesus Christ is truly God and truly man. He is fully and completely both at the same time, showing us the true nature of each. He is not some mixture of humanity and divinity, creating a third kind of being, like a horse and donkey becoming a mule. The Son of God remained God – he never gave up being God, but he added to his divinity real humanity. As God incarnate, the divine subject made real human experience his own, and since the incarnation, the Son of God will forever be human.

Against Arius, the Chalcedonian Creed asserts that Jesus was truly God. Against Apollinaris, it asserts that he was truly man. Against Eutyches, it asserts that Jesus’ deity and humanity were not changed into something else. And against Nestorius, the Creed asserts that Jesus was not divided but was one Person and in this one Person are two distinct natures, which are divine and human in all their fullness.