...Only from inside the Church's mystery of communion is the "identity" of the lay faithful made known and their fundamental dignity revealed. Only within the context of this dignity can their vocation and mission in the Church and in the world be defined...
...In giving a response to the question "Who are the lay faithful?" the [Second Vatican] Council went beyond previous interpretations which were predominantly negative. Instead it opened itself to a decidedly positive vision and displayed a basic intention of asserting the full belonging of the lay faithful to the Church and to its mystery. At the same time it insisted on the unique character of their vocation which is, in a special way, to "seek the Kingdom of God by engaging in temporal affairs and ordering them according to the plan of God." "The term 'lay faithful'"—we read in the Constitution on the Church, Lumen Gentium—"is here understood to mean all the faithful except those in Holy Orders and those who belong to a religious state sanctioned by the Church. Through Baptism the lay faithful are made one body with Christ and are established among the People of God. They are in their own way made sharers in the priestly, prophetic and kingly office of Christ. They carry out their own part in the mission of the whole Christian people with respect to the Church and the world."
Pius XII once stated: "The Faithful, more precisely the lay faithful, find themselves on the front lines of the Church's life; for them the Church is the animating principle for human society. Therefore, they in particular, ought to have an ever-clearer consciousness not only of belonging to the Church, but of being the Church, that is to say, the community of the faithful on earth under the leadership of the Pope, the head of all, and of the Bishops in communion with him. These are the Church..."
According to the biblical image of the vineyard, the lay faithful, together with all the other members of the Church, are branches engrafted to Christ the true vine, and from him derive their life and fruitfulness.
Incorporation into Christ through faith and Baptism is the source of being a Christian in the mystery of the Church. This mystery constitutes the Christian's most basic "features" and serves as the basis for all the vocations and dynamism of the Christian life of the lay faithful (cf. Jn 3:5). In Christ who died and rose from the dead, the baptized become a "new creation" (Gal 6:15; 2 Cor 5:17), washed clean from sin and brought to life through grace.
Therefore, only through accepting the richness in mystery that God gives to the Christian in Baptism is it possible to come to a basic description of the lay faithful.
It is no exaggeration to say that the entire existence of the lay faithful has as its purpose to lead a person to a knowledge of the radical newness of the Christian life that comes from Baptism, the sacrament of faith, so that this knowledge can help that person live the responsibilities which arise from that vocation received from God. In arriving at a basic description of the lay faithful we now more explicitly and directly consider among others the following three fundamental aspects: Baptism regenerates us in the life of the Son of God; unites us to Christ and to his Body, the Church; anoints us in the Holy Spirit, making us spiritual temples.
We here recall Jesus' words to Nicodemus: "Truly, truly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God" (Jn 3:5). Baptism, then, is a rebirth, a regeneration.
In considering this aspect of the gift which comes from Baptism, the Apostle Peter breaks out into song: "Blessed be the God and Father of our Lord Jesus Christ! By his great mercy we have been born anew to a living hope through the resurrection of Jesus Christ from the dead and to an inheritance which is imperishable, undefiled and unfading" (1 Pt 1:3-4). And he calls Christians those who have been "born anew, not of perishable seed but of imperishable, through the living and abiding word of God" (1 Pt 1:23).
With Baptism we become children of God in his only-begotten Son, Jesus Christ. Rising from the waters of the baptismal font, every Christian hears again the voice that was once heard on the banks of the Jordan River: "You are my beloved Son; with you I am well pleased" (Lk 3:22). From this comes the understanding that one has been brought into association with the beloved Son, becoming a child of adoption (cf. Gal 4:4-7) and a brother or sister of Christ. In this way the eternal plan of the Father for each person is realized in history: "For those whom he foreknew he also predestined to be conformed to the image of his Son, in order that he might be the first-born among many brethren" (Rom 8:29).
It is the Holy Spirit who constitutes the baptized as Children of God and members of Christ's Body. St. Paul reminds the Christians of Corinth of this fact: "For by one Spirit we are all baptized into one body" (1 Cor 12:13), so that the Apostle can say to the lay faithful: "Now you are the body of Christ and individually members of it" (1 Cor 12:27); "and because you are sons, God has sent the Spirit of his Son into our hearts" (Gal 4:6; cf. Rom 8:15-16).