The Family, a Communion of Persons
In matrimony and in the family a complex of interpersonal relationships is set up-married life, fatherhood and motherhood, filiation and fraternity-through which each human person is introduced into the “human family” and into the “family of God,” which is the Church.
(notice that JP2 uses quotations around other uses of the word family)
Christian marriage and the Christian family build up the Church: for in the family the human person is not only brought into being and progressively introduced by means of education into the human community, but by means of the rebirth of baptism and education in the faith the child is also introduced into God’s family, which is the Church.
The human family, disunited by sin, is reconstituted in its unity by the redemptive power of the death and Resurrection of Christ. Christian marriage, by participating in the salvific efficacy of this event, constitutes the natural setting in which the human person is introduced into the great family of the Church.
The commandment to grow and multiply, given to man and woman in the beginning, in this way reaches its whole truth and full realization.
The Church thus finds in the family, born from the sacrament, the cradle and the setting in which she can enter the human generations, and where these in their turn can enter the Church.
21. Conjugal communion constitutes the foundation on which is built the broader communion of the family, of parents and children, of brothers and sisters with each other, of relatives and other members of the household.
The Christian family is also called to experience a new and original communion which confirms and perfects natural and human communion. In fact the grace of Jesus Christ, "the first-born among many brethren “ is by its nature and interior dynamism “a grace of brotherhood,” as St. Thomas Aquinas calls it. The Holy Spirit, who is poured forth in the celebration of the sacraments, is the living source and inexhaustible sustenance of the supernatural communion that gathers believers and links them with Christ and with each other in the unity of the Church of God. The Christian family constitutes a specific revelation and realization of ecclesial communion, and for this reason too it can and should be called "the domestic Church.”
It can’t be a good development when the affirmation of the family is seen as something divisive.