The Catholic Church distinguishes between homosexual inclination and homosexual acts. While homosexual inclination is “objectively disordered”, it is not in itself a sin. Homosexual acts, however are “acts of grave depravity”, “intrinsically disordered” and “contrary to natural law”.
Roman Catholic interpretation of the scriptures on homosexuality is expressly based on its tradition and its interpretation of natural law (a fundamental concept of Catholic theology).
In accordance with the tradition, “Love the sinner, hate the sin”, the Church condemns discrimination against gays.
The Catechism of the Catholic Church:
2357 Homosexuality refers to relations between men or between women who experience an exclusive or predominant sexual attraction toward persons of the same sex. It has taken a great variety of forms through the centuries and in different cultures. Its psychological genesis remains largely unexplained. Basing itself on Sacred Scripture, which presents homosexual acts as acts of grave depravity, tradition has always declared that “homosexual acts are intrinsically disordered.” They are contrary to the natural law. They close the sexual act to the gift of life. They do not proceed from a genuine affective and sexual complementarity. Under no circumstances can they be approved.
2358 The number of men and women who have deep-seated homosexual tendencies is not negligible. This inclination, which is objectively disordered, constitutes for most of them a trial. They must be accepted with respect, compassion, and sensitivity. Every sign of unjust discrimination in their regard should be avoided. These persons are called to fulfill God’s will in their lives and, if they are Christians, to unite to the sacrifice of the Lord’s Cross the difficulties they may encounter from their condition.
2359 Homosexual persons are called to chastity. By the virtues of self-mastery that teach them inner freedom, at times by the support of disinterested friendship, by prayer and sacramental grace, they can and should gradually and resolutely approach Christian perfection.