The Church, obedient to the Lord who founded her and gave to her the sacramental life, celebrates the divine plan of the loving and live-giving union of men and women in the sacrament of marriage. It is only in the marital relationship that the use of the sexual faculty can be morally good. A person engaging in homosexual behaviour therefore acts immorally.
To chose someone of the same sex for one’s sexual activity is to annul the rich symbolism and meaning, not to mention the goals, of the Creator’s sexual design. Homosexual activity is not a complementary union, able to transmit life; and so it thwarts the call to a life of that form of self-giving which the Gospel says is the essence of Christian living. This does not mean that homosexual persons are not often generous and giving of themselves; but when they engage in homosexual activity they confirm within themselves a disordered sexual inclination which is essentially self-indulgent.
As in every moral disorder, homosexual activity prevents one’s own fulfillment and happiness by acting contrary to the creative wisdom of God. The Church, in rejecting erroneous opinions regarding homosexuality, does not limit but rather defends personal freedom and dignity realistically and authentically understood.
Thus, the Church’s teaching today is in organic continuity with the Scriptural perspective and with her own constant Tradition. Though today’s world is in many ways quite new, the Christian community senses the profound and lasting bonds which join us to those generations who have gone before us, “marked with the sign of faith”.
Nevertheless, increasing numbers of people today, even within the Church, are bringing enormous pressure to bear on the Church to accept the homosexual condition as though it were not disordered and to condone homosexual activity. Those within the Church who argue in this fashion often have close ties with those with similar views outside it. These latter groups are guided by a vision opposed to the truth about the human person, which is fully disclosed in the mystery of Christ. They reflect, even if not entirely consciously, a materialistic ideology which denies the transcendent nature of the human person as well as the supernatural vocation of every individual.
The Church’s ministers must ensure that homosexual persons in their care will not be misled by this point of view, so profoundly opposed to the teaching of the Church. But the risk is great and there are many who seek to create confusion regarding the Church’s position, and then to use that confusion to their own advantage. — from On the Pastoral Care of Homosexual Persons (1986), signed by Joseph Cardinal Ratzinger