We see then the purpose of the first advent of Christ. The Logos took upon Himself a human nature, the Word became flesh to effect our redemption by fulfilling the role of the perfect Mediator between God and man. The new Adam is our champion, our representative, who satisfies the demands of God’s law for us and wins for us the blessing that God promised to His creatures if we would obey His law.
Along with the great theologian and philosopher Anselm of Canterbury we ask the question, Cur deus homo? Why the God-man? When we look at the biblical answer to that question, we see that the purpose behind the incarnation of Christ is to fulfill His work as God’s appointed Mediator. It is said in 1 Timothy 2:5: “For there is one God and one Mediator between God and men, the Man Christ Jesus, who gave Himself ….” Now, the Bible speaks of many mediators with a small or lower case “m.” A mediator is an agent who stands between two parties who are estranged and in need of reconciliation. But when Paul writes to Timothy of a solitary Mediator, a single Mediator, with a capital “M,” he’s referring to that Mediator who is the supreme Intercessor between God and fallen humanity. This Mediator, Jesus Christ, is indeed the God-man.
In the early centuries of the church, with the office of mediator and the ministry of reconciliation in view, the church had to deal with heretical movements that would disturb the balance of this mediating character of Christ. Our one Mediator, who stands as an agent to reconcile God and man, is the One who participates both in deity and in humanity. In the gospel of John, we read that it was the eternal Logos, the Word, who became flesh and dwelt among us. It was the second person of the Trinity who took upon Himself a human nature to work out our redemption. In the fifth century at the Council of Chalcedon in 451, the church had to fight against a sinister teaching called the Monophysite heresy. The term monophysite is derived from the prefix mono, which means “one,” and from the root phusis, which means “nature” or “essence.” The heretic Eutyches taught that Christ, in the incarnation, had a single nature, which he called a “theanthropic nature.” This theanthropic nature (which combines the word theos, meaning “God,” and anthropos, meaning “man”) gives us a Savior who is a hybrid, but under close scrutiny would be seen to be one who was neither God nor man. The Monophysite heresy obscured the distinction between God and man, giving us either a deified human or a humanized deity. It was against the backdrop of this heresy that the Chalcedonian Creed insisted Christ possesses two distinct natures, divine and human. He is vere homo (truly human) and vere Deus (truly divine, or truly God). These two natures are united in the mystery of the incarnation, but it is important according to Christian orthodoxy that we understand the divine nature of Christ is fully God and the human nature is fully human. So this one person who had two natures, divine and human, was perfectly suited to be our Mediator between God and men. An earlier church council, the Council of Nicea in 325, had declared that Christ came “for us men, and for our salvation.” That is, His mission was to reconcile the estrangement that existed between God and humanity.