On September 17, 1983, Pope John Paul II told a group of priests that “contraception is to be judged objectively so profoundly unlawful as never to be, for any reason, justified. To think or to say the contrary is equal to maintaining that, in human life, situations may arise in which it is lawful not to recognize God as God.”
On June 5, 1987, the Holy Father warned clergy and theologians of their grave obligation to faithfully transmit the Church’s teaching on this subject: “A grave responsibility derives from this: those who place themselves in open conflict with the law of God, authentically taught by the Church, guide spouses along a false path. The Church’s teaching on contraception does not belong to the category of matter open to free discussion among theologians. Teaching the contrary amounts to leading the moral consciences of spouses into error.” Pope John Paul II also explained that contraception contradicts and is opposed to true love: “Thus the innate language that expresses the total reciprocal self-giving of husband and wife is overlaid, through contraception, by an objectively contradictory language, namely, that of not giving oneself totally to the other. This leads not only to a positive refusal to be open to life but also to a falsification of the inner truth of conjugal love, which is called upon to give itself in personal totality.” (Familiaris Consortio, #32)
The Holy Father has explained that when contraception is used, the marital act ceases to be an act of love:
In the conjugal act it is not licitly to separate the unitive aspect from the procreative aspect, because both the one and the other pertain to the intimate truth of the conjugal act. The one is activated together with the other and in a certain sense the one by means of the other. This is what the encyclical teaches (cf. Humanae Vitae, 12). Therefore, in such a case the conjugal act, deprived of its interior truth because it is artificially deprived of its procreative capacity, ceases also to be an act of love. (General Audience of August 22, 1984)
The constant teaching of the Church was again stated on March 1, 1997 when the Vatican’s Pontifical Council for the Family issued a Vade Mecum for Confessors Concerning Some Aspects of the Morality of Conjugal Life. Included in this document is the following statement:
The Church has always taught the intrinsic evil of contraception, that is, of every marital act intentionally rendered unfruitful. This teaching is to be held as definitive and irreformable. Contraception is gravely opposed to marital chastity; it is contrary to the good of the transmission of life (the procreative aspect of matrimony) and to the reciprocal self-giving of the spouses (the unitive aspect of matrimony); it harms true love and denies the sovereign role of God in the transmission of life (n. 24).
As Pope John Paul II has stated, “The heart has become a battlefield between love and lust. The more lust dominates the heart, the less the heart experiences the nuptial meaning of the body. It becomes less sensitive to the gift of the person, which expresses that meaning in the mutual relations of the man and woman.” (General audience of July 23, 1980)