The incarnation of the Son of God took place in order that the work of redemption, decreed by God from eternity, might be accomplished, John 17, 4; 3, 16; Matt. 18, 11; Luke 19, 10; 1 Tim. 1, 15. The Augsburg Confession declares Art. III: "The Word, that is, the Son of God, did assume the human nature in the womb of the blessed Virgin Mary . . . that He might reconcile the Father unto us and to be a Sacrifice, not only for original guilt, but also for all actual sins of men.” Hence, whatever Christ in His state of humiliation did as the God-man, Luke 1, 30. 31; Matt. 1, 21. 25; Luke 2,21, and what He still does as such in His state of exaltation belongs to His divine office, or work.
Of the mediatorial office of Christ Quenstedt writes: “The mediatorial office is the function, belonging to the whole person of the God-man and consisting of theanthropic actions, by which function Christ in, with, and through both natures perfectly executed, by way of acquisition and application, and is even now executing, all things that are necessary for our salvation.” (Doctr . Theol., p. 338.) More briefly expressed, Christ’s mediatorial work embraces all that He did to effect our salvation and all that He still does to make salvation available to men.
If the question is asked, Since when did Christ execute His mediatorial office? we reply: a) Not only since the time of His baptism, which was indeed the solemn induction into His public mediatorial ministry, but b) from the very moment of His incarnation, since His conception, birth, circumcision, filial obedience, etc., were accomplished for the salvation of sinful and lost mankind. Gal. 4, 4. 5; 1 John 3, 8.
Those who assume that the Son of God became incarnate for reasons other than the redemption of mankind (Socinians, Pelagians, Schleiermacher, modern theologians: “Christ came as the second Adam to perfect creation”) oppose Scripture, which expressly teaches that Christ came into the world only to save sinners, John 3,16; 1 Tim. 1,15; 1 John 4, 9. 10.
If it is asked why the λόγος waited four thousand years before He became incarnate, we have no other answer in Scripture than that it so pleased God, Gal. 4, 4. 5.
As the Savior of sinful mankind, Christ had to accomplish three distinct works: a) He had to teach men the way of salvation, Luke 4, 18; John 1, 18; Heb. 1, 1; Matt. 17, 5. b) He had to reconcile the world unto God, 2 Cor. 5,18. 19; Matt. 20, 28; Rom. 5,10; 1 John 2, 2. c) He had to rule over the Church as its Head and over all things as the sovereign King of the universe, Luke 1, 33; Eph. 1, 20—23; John 18, 33—37. Hence we speak of the threefold office of Christ: a) the prophetic (munus propheticum), b) the sacerdotal (munus sacerdotale), and c) the kingly (munus regium). As the divine Prophet, Priest, and King the Messiah was pictured already in the Old Testament, Deut. 18, 15—19; Ps. 110; 2,6—12.
All actions performed by Christ, our Prophet, Priest, and King, are theanthropic actions; in other words, all things necessary for our salvation axe executed by Christ according to both natures.
While the three offices were never divided, or separated, in Christ, we hold to the classification just given (munus triplex) for the sake of greater clearness in presenting Christ’s work, though some dogmaticians combine the prophetic office with the sacerdotal, obtaining in this way only two offices of Christ.