1. The Work of the Incarnation
The assuming of human nature by God the Son, the Second Person of the Blessed Trinity, is the work of all three Divine Persons. The Incarnation is the Incarnation of God the Son, not of the Father or of the Holy Spirit. Nevertheless, the Incarnation was the work of the whole Trinity. Therefore in Sacred Scripture it is sometimes attributed to God the Father ( Heb 10:5 ; Gal 4:4), to the Son himself (Phil 2:7) or to the Holy Spirit ( Lk 1:35; Mt 1:20). This emphasises that the work of the Incarnation was a single act, common to the three divine Persons. St. Augustine explained that “the fact that Mary conceived and bore a child is the work of the Trinity, since the works of the Trinity are inseparable."  This is a divine action ad extra, the effects of which are outside of God, in creatures, so that they are the work of the three Persons conjointly, since the divine Being, which is God's infinite power itself, is one and unique (cf. Catechism of the Catholic Church ,hereafter CCC, 258).
The Incarnation of the Word does not affect God's freedom, since God could have decided that the Word should not become incarnate, or that another divine Person should become incarnate. However, to say that God is infinitely free does not mean that his decisions are arbitrary, nor does it deny that love is the reason for his actions. This is why theologians generally seek the “fitting reasons" that can be glimpsed in God's various decisions as shown in the existing economy of salvation. By doing so, they are only seeking to highlight the wonderful wisdom and inner consistency in every work of God, rather than any supposed necessity on God's part.
2. The Virgin Mary, Mother of God
The Virgin Mary was predestined to be the Mother of God from all eternity, in view of the Incarnation of the Word. “In the mystery of Christ she is present even 'before the creation of the world' as the one whom the Father 'has chosen' as mother of his Son in the Incarnation. And, what is more, together with the Father, the Son has chosen her, entrusting her eternally to the Spirit of holiness."  God's choice respects Mary's freedom, since “the Father of mercies willed that the Incarnation should be preceded by assent on the part of the predestined mother, so that just as a woman had a share in bringing about death, so also a woman should contribute to life (LG 56; cf. 61)" (CCC, 488). Because of this, from the earliest times, the Fathers of the Church have seen Mary as the new Eve.
“To become the Mother of the Saviour, Mary 'was enriched by God with gifts appropriate to such a role' (LG 56)" (CCC, 490). The Archangel Gabriel greeted her at the moment of the Annunciation as “full of grace" ( Lk 1:28) before the Word had become incarnate. Through God's gifts and her response, Mary was already full of grace. The grace that Mary received made her pleasing to God and prepared her to be the virgin Mother of the Saviour. Wholly possessed by God's grace, she was able to give her free consent to the announcement of her vocation (cf. CCC, 490). “Thus, giving her consent to God's word, Mary becomes the Mother of Jesus. Espousing the divine will for salvation whole-heartedly, without a single sin to restrain her, she gave herself entirely to the person and to the work of her Son; she did so in order to serve the mystery of redemption with him and dependent on him, by God's grace (cf. LG 56)" (CCC, 494). “The Fathers of the Easter tradition call the Mother of God 'the All-Holy' ( Panagia )and celebrate her as 'free from any stain of sin, as though fashioned by the Holy Spirit and formed as a new creature' (LG 56). By the grace of God, Mary remained free of every personal sin her whole life long" (CCC, 493).
Mary was redeemed from the moment of her conception. “That is what the dogma of the Immaculate Conception confesses, as Pope Pius IX proclaimed in 1854: 'the most Blessed Virgin Mary was, from the first moment of her conception, by a singular grace and privilege of almighty God and by virtue of the merits of Jesus Christ, saviour of the human race, preserved immune from all stain of original sin' (DS 2803)" (CCC, 491). The Immaculate Conception makes clear the gratuitous love of God, since it was an initiative on God's part and not merited by Mary, but by Christ. Indeed, “'the splendour of an entirely unique holiness' by which Mary is 'enriched from the first instant of her conception' (LG 56) comes to her wholly from Christ: 'she is redeemed in a more exalted fashion by reason of the merits of her Son' (LG 53)" (CCC, 492).
Mary is the Mother of God: “In fact, the One whom she conceived as man by the Holy Spirit, who truly became her Son according to the flesh, was none other than the Father's eternal Son, the Second Person of the Holy Trinity. Hence the Church confesses that Mary is truly' Mother of God ' ( Theotokos )(cf. DS 252)" (CCC, 495). She did not engender the divinity, but the human body of the Word, to which his rational soul, created by God like all others, was immediately united, thus giving rise to the human nature that was assumed by the Word at that very instant.
Mary was always a Virgin. From the earliest times the Church has confessed in the Creed and celebrated in her liturgy “Mary …ever-Virgin" (cf. LG 52) (CCC, 499; cf. CCC, 496-507). This faith of the Church is reflected in the ancient formula “Virgin before childbirth, during childbirth and after childbirth." From the beginning, “the Church has confessed that Jesus was conceived in the womb of the Virgin Mary solely by the power of the Holy Spirit, affirming also the corporeal aspect of this event; Jesus was conceived by the Holy Spirit 'without human seed'(Lateran Council, 649; DS 503)" (CCC, 496). Mary was also a virgin during childbirth, since “she gave birth to him without detriment to her virginity, just as she had conceived him without loss of her virginity … Jesus was born of a virginal womb by a miraculous birth."  In fact “Christ's birth 'did not diminish his mother's virginal integrity but sanctified it' (LG 57)" (CCC, 499). Mary remained perpetually a virgin after childbirth. The Fathers of the Church, in their explanations of the Gospels and in their replies to certain objections, have always affirmed this fact, which manifests her total availability and absolute dedication to God's plan of salvation. St. Basil summarised this when he wrote: “those who love God will not hear that the Mother of God ceased to be a virgin at any stage." 
Mary was assumed into heaven. “The Immaculate Virgin, preserved free from any stain of original sin, was taken up body and soul into heavenly glory, when her earthly life was over, and exalted by the Lord as Queen over all things, that she might be the more fully conformed to her Son, the Lord of lords and conqueror of sin and death."  The Assumption of the Blessed Virgin is an anticipation of the resurrection of other Christians (cf. CCC, 966). Mary's royal status is based on her divine maternity and her association with the work of the Redemption.  On 1 November 1954, Pius XII instituted the feast of the Queenship of Mary. 
Mary is the Mother of the Redeemer. Because of this her divine motherhood includes her co-operation in the salvation of mankind: “Thus the daughter of Adam, Mary, consenting to the word of God, became the Mother of Jesus. Committing herself whole-heartedly and impeded by no sin to God's saving will, she devoted herself totally, as a handmaid of the Lord, to the person and work of her Son, under and with him, serving the mystery of redemption, by the grace of Almighty God. Rightly, therefore, the Fathers see Mary not merely as passively engaged by God, but as freely co-operating in the work of man's salvation through faith and obedience." 
This co-operation is also manifested in her spiritual maternity. Mary, the new Eve, is the true mother of men in the order of grace since she co-operates in the birth of the faithful to the life of grace and in their spiritual development: Mary “in a wholly singular way co-operated by her obedience, faith, hope and burning charity in the Saviour's work of restoring supernatural life to souls. For this reason she is a mother to us in the order of grace"  (cf. CCC, 968). Mary is also the mediatrix; her motherly mediation, always subordinate to the one mediation of Christ, began with her fiat at the Annunciation and continues in heaven: “Taken up to heaven she did not lay aside this saving office but by her manifold intercession continues to bring us the gifts of eternal salvation … Therefore the Blessed Virgin is invoked in the Church under the titles of Advocate, Helper, Benefactress, and Mediatrix"  (cf. CCC, 969).
Mary is the type and model of the Church: “The Virgin Mary is the Church's model of faith and charity. 'Thus she is a pre-eminent and wholly unique member of the Church' (LG 53); indeed, she is the 'exemplary realisation' of the Church (LG 63)" (CCC, 967). Paul VI, on 21 November 1964, solemnly proclaimed Mary the Mother of the Church, so as to emphasise explicitly the motherly role that the Blessed Virgin fulfils towards the Christian people. 
In view of all the above, we can understand why the Church's devotion to the Blessed Virgin Mary is an intrinsic part of Christian worship.  “The Church rightly honours 'the Blessed Virgin with special devotion. From the most ancient times the Blessed Virgin has been honoured with the title of Mother of God , to whose protection the faithful fly in all their dangers and needs … This very special devotion … differs essentially from the adoration which is given to the Incarnate Word and equally to the Father and the Holy Spirit, and greatly fosters this adoration.'  The liturgical feasts dedicated to the Mother of God (cf. SC 103) and Marian prayer such as the Rosary, express this devotion to the Virgin Mary" (CCC, 971).
3. Figures and Prophecies of the Incarnation
The previous article discussed how after the sin of our first parents, Adam and Eve, God did not abandon mankind, but promised us a Saviour (cf. Gen 3:15; CCC, 410).
After original sin and the promise of a Redeemer, God himself took the initiative once again and established a Covenant with men: with Noah after the flood (cf. Gen 9-10) and afterwards above all with Abraham (cf. Gen 15-17), to whom he promised many descendants whom he would make a great people, giving them a new land, and in whom one day all nations would be blessed. The Covenant was renewed later with Isaac (cf. Gen 26:2-5) and with Jacob (cf. Gen 28:12-15; 35:9-12). In the Old Testament, the Covenant reached its highest expression with Moses (cf. Ex 6:2-8; Ex 19-34).
An important moment in the history of the relationship between God and Israel was Nathan's prophecy (cf. 2 Sam 7:7-15), which announced that the Messiah would be a descendant of David and that he would reign over all peoples, not only over Israel. Other prophetic texts told that his birth would take place in Bethlehem (cf. Mic 5:1), that he would come from the seed of David (cf. Is 11:1; Jer 23:5); that he would be given the name “Emmanuel," that is, God with us (cf. Is 7:14); that he would be called “Mighty God, Everlasting Father, Prince of Peace" (Is 9:5), etc. Besides the texts that describe the Messiah as king and a descendant of David, there are others that prophesy the redemptive mission of the Messiah, calling him the Servant of God, man of sorrows, who will make peace and reconcile us in one body (cf. Eph 2:14-18): Is 42:1-7; 49:1-9; 50:4-9; 52:13-53:12. In this context the text of Dan 7:13-14 is important, about the Son of man, who mysteriously, through humility and abasement, overcomes the human condition and restores the messianic kingdom in its final and permanent phase (cf. CCC, 440).
The principal “types" or figures of the Redeemer in the Old Testament are the innocent Abel, the high priest Melchizedek, the sacrifice of Isaac, Joseph sold by his brothers, the paschal lamb, the bronze serpent raised by Moses in the desert, and the prophet Jonah.
4. The Names of Christ
Throughout the centuries many names and titles have been attributed to Christ by theologians and spiritual authors. Some are taken from the Old Testament, others from the New. Some are used or accepted by Jesus himself; others have been applied to him by the Church throughout the centuries. The following are the main and most frequently-used names.
Jesus (cf. CCC, 430-435), which in Hebrew means “God saves." “At the Annunciation, the Angel Gabriel gave him the name Jesus as his proper name, which expresses both his identity and his mission" (CCC, 430), that is, he is the Son of God made man in order to save “his people from their sins" ( Mt 1:21). The name Jesus “signifies that the very name of God is present in the person of his Son (cf. Acts 5:41; 3 Jn 7), made man for the universal and definitive redemption from sins. It is the divine name that alone brings salvation (cf. Jn 3:18; Acts 2:21), and henceforth all can invoke his name, for Jesus united himself to all men through his Incarnation" (CCC, 432). “The name of Jesus is at the heart of Christian prayer" (cf. CCC, 435).
Christ (cf. CCC, 436-440), the name that comes from the Greek translation of the Hebrew term “Messiah," which means “anointed." It became the name proper to Jesus “because he accomplished perfectly the divine mission that 'Christ' signifies. In effect, in Israel those consecrated to God for a mission that he gave were anointed in his name" (CCC, 436). This was the case for priests, kings and, exceptionally, prophets. All the more would it apply to the Messiah whom God would send to restore his kingdom definitively. Jesus fulfilled the messianic hope of Israel in his triple function as priest, prophet and king (cf. ibid. ). “Jesus accepted his rightful title of messiah (cf. Jn 4:25-26; 11:27), though with some reserve because it was understood by some of his contemporaries in too human a sense (cf. Mt 22:41-46), as essentially political (cf. Jn 6:15; Lk 24:21)" (CCC, 439).
Jesus Christ is the Only Son of God (cf. CCC, 441-445). Jesus' sonship in relation to his Father is not an adoptive sonship like ours, but the natural sonship of God, that is to say, “the unique and eternal relationship of Jesus Christ to God his Father: he is the only Son of the Father (cf. Jn 1:14, 18; 3:16, 18); he is God himself (cf. Jn 1:1). To be a Christian one must believe that Jesus Christ is the Son of God (cf. Acts 8:37; 1 Jn 2:23)" (CCC, 454). The Gospels “report that at two solemn moments, the Baptism and the Transfiguration of Christ, the voice of the Father designates Jesus his 'beloved Son' ( Mt 3:17; 17:5). Jesus calls himself the 'only Son of God' ( Jn 3:16) and by this title affirms his eternal pre-existence" (CCC, 444).
Lord (cf. CCC, 446-451): “In the Greek translations of the Old Testament, the ineffable Hebrew name YHWH, by which God revealed himself to Moses (cf. Ex 3:14) is rendered as Kyrios , 'Lord.' From then on Lord becomes the more usual name by which to indicate the divinity of Israel's God. The New Testament uses this full sense of the title 'Lord' both for the Father and – what is new – for Jesus, who is thereby recognised as God Himself (cf. 1 Cor 2:8)" (CCC, 446). By attributing to Jesus the divine title of Lord, “the first confessions of the Church's faith affirm from the beginning ( Acts 2:34-36) that the power, honour and glory due to God the Father are due also to Jesus (cf. Rom 9:5; Tit 2:13; Rev 5:13), because 'he was in the form of God' ( Phil 2:6), and the Father manifested the sovereignty of Jesus by raising him from the dead and exalting him into his glory (cf. Rom 10:9; 1 Cor 12:3; Phil 2:11)" (CCC, 449). “Christian prayer, both liturgical and personal, is characterised by the title 'Lord'" (cf. CCC, 451).
5. Christ is the only perfect Mediator between God and men. He is Teacher, Priest and King .
“Jesus Christ is true God and true man, in the unity of his divine person; for this reason he is the one and only mediator between God and man" (CCC, 480). In the New Testament the most profound expression of Christ's mediation is to be found in the first letter to Timothy: For there is one God and there is one mediator between God and men, the man Jesus Christ, who gave himself as a ransom for all (1 Tim 2:5). These words present the Mediator and his action. In the letter to the Hebrews Christ is presented as the mediator of a New Covenant (cf. Heb 8:6; 9:15; 12:24). Jesus Christ is mediator because he is perfect God and perfect man, but he is mediator in and through his humanity. These texts of the New Testament present Christ as prophet and the one who reveals the truth, as high priest and as the Lord of all creation. These are not three distinct ministries, but three different aspects of the saving function of the one mediator.
Christ is the prophet announced in Deuteronomy (18:18). The people considered Jesus to be a prophet (cf. Mt 16:14; Mk 6:14-16; Lk 24:19). The beginning of the Letter to the Hebrews sets this out clearly. But Christ is more than a prophet: he is the Teacher, that is, the one who teaches by his own authority, with an authority unknown until then, which surprised those who listened to him. The supreme character of Jesus' teachings is founded on the fact that he is God and man. Jesus not only teaches the truth, He is the Truth, made visible in the flesh. Christ, the eternal Word of the Father, “is the Father's one, perfect and unsurpassable Word. In him he has said everything; there will be no other word than this one" (CCC, 65). Christ's teaching is also definitive in the sense that, with it, God's Revelation to men in history has been finally fulfilled.
Christ is priest. Jesus Christ's mediation is a priestly mediation. In the Letter to the Hebrews, which has Christ's priesthood as its central theme, Jesus Christ is presented as the High Priest of the New Covenant, “'high priest after the order of Melchizedek' ( Heb 5:10); 'holy, blameless, unstained' ( Heb 7:26), who “by a single offering has perfected for all time those who are sanctified' ( Heb 10:14), that is, by the unique sacrifice of the cross" (CCC, 1544). In the same way as the sacrifice of Christ – his death on the Cross – is unique because of the unity that exists between the priest and the victim (of infinite value), so also his priesthood is unique. He is the one victim and the one priest. The sacrifices of the Old Testament were a figure of Christ's sacrifice, and they received their value precisely because they were orientated to Christ. Christ's priesthood, the eternal priesthood, is participated in by the ministerial priesthood and by the priesthood of the faithful, which neither add to nor take away from that of Christ (cf. CCC, 1544-1547).
Christ is King. He is King not only as God, but also as man. Christ's sovereignty is a fundamental aspect of his saving mediation. Christ saves because he has the effective power to do so. The faith of the Church affirms Christ's royalty and confesses in the Creed that “his kingdom will have no end," thus repeating what the archangel Gabriel said to Mary (cf. Lk 1:32-33). Christ's royal dignity had already been announced in the Old Testament (cf. Ps 2:6; Is 7:6; 11:1-9; Dan 7:14). However, Christ did not speak much about his royalty, since among the Jews of his day a worldly concept of the messianic Kingdom was very widespread. He acknowledged it, indeed, at a particularly solemn moment, when he replied to a question of Pilate's: You say that I am a king ( Jn 18:37). Christ's royalty is not metaphorical, but real, and includes the power to legislate and to judge. It is a royalty based on the fact that he is the Word incarnate and that he is our Redeemer. His kingdom is spiritual and eternal. It is a kingdom of holiness and justice, of love, truth and peace.  Christ exercises his royalty by drawing all men to himself through his death and resurrection (cf. Jn 12:32). Christ, the King and Lord of the universe, became the servant of all, not having “come to be served, but to serve, and to give his life as a ransom for many ( Mt 20:28)" (CCC, 786). All the faithful “participate in these three offices of Christ and bear the responsibilities for mission and service that flow from them" (CCC, 783).
6. The whole of Christ's life is redemptive
Concerning the events in Christ's life, “the Creed speaks only about the mysteries of the Incarnation (conception and birth) and the Paschal mystery (passion, crucifixion, death, burial, descent into hell, resurrection and ascension). It says nothing explicitly about the mysteries of Jesus' hidden or public life, but the articles of faith concerning his Incarnation and Passover do shed light on the whole of his earthly life" (CCC, 512).
The whole of Christ's life is redemptive and any human action of his possesses a transcendent salvific value. Even in the simplest and apparently least important of Jesus' actions there is an effective exercise of his mediation between God and men, since they are all the actions of the incarnate Word. St. Josemaria understood this teaching with particular depth. He taught people to turn all the paths of the earth into divine paths of holiness: “When the fullness of time comes to fulfil that mission … a child is born in Bethlehem. He it is who is to redeem the world. But before he speaks he loves with deeds. It is no magic formula he brings, because he knows that the salvation he offers must pass through human hearts. What does he first do? He laughs and cries and sleeps, as a helpless baby, although he is God incarnate. And he does this so that we may fall in love with him, so that we may learn to take him in our arms." 
The years of Christ's hidden life are not simply a preparation for his public ministry, but are truly redemptive actions, directed towards the consummation of the Paschal Mystery. The fact that Jesus shared the condition of most people for the greater part of his life is of great theological relevance: his daily family life and his life of work in Nazareth. Nazareth is therefore a lesson in family life, and a lesson in work.  Christ also carries out our redemption during the many years of work in his hidden life. Thus he gave to the daily work of Christians, and to that of millions of men and women of good will, all its divine significance in the history of salvation: “The fact that Jesus grew up and lived just like us shows us that human existence and all the ordinary activities of men have a divine meaning." 
José Antonio Riestra
Catechism of the Catholic Church, 484-570, 720-726 and 963-975
Benedict XVI, Joseph Ratzinger, Jesus of Nazareth , Bloomsbury, London, 2007
J. L. Bastero, Mary, Mother of the Redeemer: A Mariology Textbook , Four Courts Press, 2006
F. Ocáriz, L. F. Mateo Seco and J. A. Riestra, The Mystery of Jesus Christ: A Christology and Soteriology Textbook , trans. Michael Adams and James Gavigan. Portland, OR: Four Courts Press, 1994
 St. Augustine, De Trinitate, 2, 5, 9; cf. Lateran Council IV: DS 801
 John Paul II, Enc. Redemptoris Mater, 25 March 1987, 8; cf. Pius IX, Bull Ineffabilis Deus; Pius XII, Bull Munificentissimus Deus, AAS 42 (1950) 9768; Paul VI, Apost. Exhort. Marialis Cultus, 25; CIC, 488
 St. Leo the Great, Ep. Lectis Dilectionis Tuae, DS 291-294
 St. Basil, In Christi Generationem, 5
 Vatican Council II, Const. Lumen Gentium , 59; cf. the proclamation of the dogma of the Assumption of the Blessed Virgin Mary by Pope Pius XII in 1950; DS 3903
 Cf. Pius XII, Enc. Ad Coeli Reginam, 11 October 1954; AAS 46 (1954) 625-640
 Cf. AAS 46 (1954) 662-666
 Vatican Council II, Const. Lumen Gentium, 56
 Ibid., 61
 Ibid., 62
 Cf. AAS 56 (1964) 1015-1016
 Cf. Paul VI, Exhort. Marialis Cultus, 56
 Vatican Council II, Const. Lumen Gentium, 66
 Cf. Pius XI, Enc. Quas Primas, 11 November 1925, AS 17 (195) 599
 Cf. Roman Missal, Preface of the Mass of Christ the King
 St. Josemaria, Christ is Passing By, 36
 Cf. Paul VI, Speech in Nazareth, 5 January 1964: Insegnamenti di Paolo VI 2 (1964) 25
 St. Josemaria, Christ is Passing By, 14