The Catholic belief system is a very complex one for some to understand if you are not catholic yourself. The Catholic Church believes that the Bible must be interpreted, which they do using the Tradition of the Apostles. Apostolic Succession is the passing down of authority from apostles to their successors, such as the Pope and Bishop.
Discussion
In morals, as in faith, the key is to follow what God revealed in Jesus Christ. Moral theology is powered by what Jesus Christ bequeathed to his church and reaching today's Christians through writing, of tradition and the Magisterium, as a faithful interpreter and preserver of both.
The Catechism of the Catholic Church is part of the Magisterium: contains the substance of the teaching of the Church. The Catholic has the essence of the moral teachings of Jesus Christ in the third part of the Catechism of the Catholic Church (nos. 1699 to 2557). To probe the problems of social doctrine, or morality of marriage, etc.. There are specialized books, the encyclicals of the popes, as the "Humanae Vitae," the "Redemptor Hominis" of John Paul II, and other documents of the Holy See, as the statement "As human beings," the Instruction "Donum Vitae" etc.
Well, for the priests of parallel teaching, no acts in themselves good or bad.
The Church, however, has always taught that there are acts that are always bad, regardless of the intent with which they performed and the resulting consequences (inherently bad).
Fr Klaus Demmer who taught at the Pontifical Gregorian University in Rome, says that "there will have to rethink the theorem of the shares" as "dishonest. Asserts that" there is no doubt that the examples in a way convincing, but further effort is required semantic "(p. 116 and 290-296, the father's study grants for students Demmer).
The author boils down to "examples" that "will have to rethink the actions that the Magisterium itself identifies as bad", such a position contradicts the Catechism of the Catholic Church (nos. 1755 and 1756) in a fundamental (and cites the "Humanae Vitae" in nn. 12 and 14; Donum Vitae II B 2; Veritatis Splendor 79-83), such examples should rethink your words are: masturbation (New Catechism No. 2352), rape (b. 2356) , homosexuality (b. 2357), artificial contraception (b. 2370), assisted procreation (b. 2376), prostitution (b. 2355).