1) Opus Dei is a prelature because it is governed and directed by a prelate with the hierarchical powers of Orders and the prelatic powers conferred by papal juridical act to gather lay faithful and ministerial priests for a universal mission within the Church and the world. That mission is the sanctification of ordinary work by both laity and clergy without leaving one’s state in life .
2) The nature of priesthood is mediation (CCC # 1544). The priesthood of Jesus Christ is a revolution in that the terms of the mediation are between the Self of Christ and the Father. This means that Jesus Christ is priest of His own existence whereby as divine Person he masters His human will (that is “His”) and obeys in the totality of His Divine Self as God-man to death on the Cross. This Christology discloses the priestly anthropology of human existence. St. Josemaria Escriva called it "priestly soul."
3) We are all sacramentally inserted into that one priesthood of Christ: laity into the “common priesthood” by baptism, ministerial priests by Orders. These sacramental insertions, although radically equal, are irreducibly different in that the mission of the laity is to the world while the ministerial priest is to the service of the laity.
4) The priestly dimension of both laity and ministers demands a radical giving of the self to each other. The service of the ministerial priest is to make it possible for the layman to make the self-gift by means of providing the Holy Sacrifice of the Mass, the preaching of the Supernatural Work, and the administration of the Sacraments, especially Penance. The service of the layman is to actively need the priest, which is the most profound form of affirmation and identity giving.
This mutual and reciprocal self-giving on the part of these irreducibly different protagonists of the one priesthood of Christ form “communio” (that is not “community” made of substantially independent but “associated” individuals. Rather, the communio is such that one cannot be or function without the other, like “family.” This is “oneness,” not unity. It is the “aboriginal relationship” that obtained in the Church from the beginning, and the reason why Opus Dei is “a little bit of the Church,” and yet not a particular Church (diocese), and this again because the prelate does not geographically instantiate the one Catholic Church in any one place.
4) The principal mission of the Prelate is not jurisdictional such as to command and exact obedience. The principal mission is to “engender sons and daughters,” i.e. to be “father.” The deep principle enunciated by then-Joseph Ratzinger is the necessity that the person has for affirmation and love in order to become actualized as person and to have an identity. This only comes from love. Ratzinger wrote: “Something strange happens here. We have seen that the inability to accept one’s I leads to the inability to accept a thou. But how does one go about affirming, assenting to, one’s I? The answer may perhaps be unexpected: We cannot do so by our own efforts alone. Of ourselves, we cannot come to terms with ourselves. Our I becomes acceptable to us only if it has first become acceptable to another I. We can love ourselves only if we have first been loved by someone else. The life a mother gives to her child is not just physical life; she gives total life when she takes the child’s tears and turns them into smiles. It is only when life has been accepted and is perceived as accepted that it becomes also acceptable. Man is that strange creature that needs not just physical birth but also appreciation if he is to subsist.”
5) This love that is endemic to the position of being the Prelate is the dynamic that grounds all his functions. D. Pedro Rodriguez remarks: “what is decisive is neither his ‘jurisdiction’ nor their obedience. Rather, what truly defines Opus Dei’s prelate is his ‘fatherhood,’ his role as a pastor who is a father to all the prelature’s faithful. That is why in Opus Dei he is usually called ‘Father.’ The prelate’s role in the life of Opus Dei deeply configures the prelature.” In a word, the “Father” must engender the Prelature, and continue to engender it by his love for his sons and daughters.
6) What does all this have to do with the anniversary of the Prelate’s ordination to the priesthood? This love that the Prelate must have transcends his natural abilities. The ministerial and therefore hierarchical (sacred origin) powers conferred by Orders together with the power conferred on him by the juridical act of the Pope enable him to love in a unique way with the heart of Christ.
7) The actual love depends on personal correspondence to this grace of state and that in turn depends on our reciprocal prayer and sacrifice for him. As communio, we cannot do what we are supposed to do without him, and he cannot do what he is supposed to without us. Consummati in unum.
 J. Ratzinger, “Principles of Catholic Theology” Ignatius (1987) 79-80.
 Pedro Rodriguez, “The Place of Opus Dei in the Church,” Opus Dei in the Church Scepter (1994) 56.