When Humanae Vitae was released on 25 July 1968, the welcome was not warm. Very promptly, many priests and theologians spoke against the encyclical. On 30 July 1968, a group of 87 Catholic theologians, including many priests and a few lay theologians, made a public statement contradicting its teaching. The statement said, in part:
“The encyclical is not an infallible teaching. History shows that a number of statement of similar or even greater authoritative weight have subsequently been proven inadequate or even erroneous. Past authoritative statements on religious liberty, interest-taking, the right to silence and the ends of marriage have all been corrected at a later date.”
“It is common teaching in the church that Catholics may dissent from authoritative, non-infallible teachings of the magisterium when sufficient reasons for so doing exist. Therefore, as Roman Catholic theologians, conscious of our duty and our limitations, we conclude that spouses may responsibly decide according to their conscience that artificial contraception in some circumstances is permissible and indeed necessary to preserve and foster the values and sacredness of marriage.” 
One of the leaders of the group was Fr. Charles Curran, then a professor at Catholic University. Curran was later rebuked by the CDF, under then-Cardinal Ratzinger. But at the time, he was one of the most prominent Catholic theologians in America.
At the same time, the 100-member Association of Washington Priests released a statement agreeing with the theologians’ statement.
“This dissenting position is perfectly compatible, we fell, to loyalty to Christ and the church. The integral pastoral ministry must take into account not papal statements alone, but also the practical day-to-day lives of those who are striving to live in the grace of Christ.” 
What has changed since then? Liberal Catholics still reject the teaching of Humanae Vitae. The laity live as if Humanae Vitae was never published. Priests seldom preach against contraception. And, to make matters worse, conservative Catholic authors have recently began to radically reinterpret Humanae Vitae, distorting and diluting its teaching.
Conservative Attacks on Humanae Vitae
1. Some conservative authors claim that Humanae Vitae and other Church documents on contraception contain no prohibition against the use of contraception by unmarried persons, and that the condemnation of contraception as an intrinsically evil act applies only to its use within a valid marriage. This error excludes most uses of contraception from the condemnation of Humanae Vitae.
To the contrary, there is ample evidence that the condemnation of contraception applies without regard to marital state. Some definitions of contraception make reference to marriage, as sex outside of marriage is gravely immoral. However, the magisterium has repeatedly described contraception also as preventing conception following after any sexual act, not only marital acts. For example, the CDF document Dignitas Personae, defines contraceptives as “methods of preventing pregnancy” and as acts “which prevent conception following from a sexual act” (conceptionem impediunt post actum sexualem). 
A document from the Pontifical Academy for Life rejects “emergency contraception” — which is most often used by unmarried persons — for being both contraceptive and abortifacient.  And a CDF document forbids Catholic hospitals from cooperation with sterilization or contraception, regardless of whether the patient is married or single, Catholic or not. The term for sexual acts used in that document is not marital acts, but the more general term “actuum sexualium” (sexual act). 
For more examples, see the following articles:
2. Some claim that Humanae Vitae n. 15 can be interpreted and applied so as to justify the use of abortifacient contraception by spouses who continue to have marital relations, despite the deaths of innocent prenatals as a result. To the contrary, abortifacient contraception is intrinsically evil and always gravely immoral, and no intended end, not even a medical purpose, can justify its use by a sexually active person. Abortifacients result in a type of abortion.
* Direct abortion is not justified by the medical purpose of saving the mother’s life.
* Euthanasia is not justified by the medical purpose of reliving all suffering.
* Masturbation is not justified by the medical purpose of obtaining a specimen for diagnosis of a disease.
* The use of condoms is not justified by the medical purpose of avoiding disease transmission.
* Artificial reproduction is not justified by the medical purpose of treating infertility.
* The use of abortifacient contraception, while sexually active, is not justified by any medical purpose.
3. Some claim that Humanae Vitae contains a translation error, such that “sexual intercourse” should have been translated as “conjugal intercourse”, so as to restrict the teaching to the use of contraception in marriage. They also claim that the Latin term “conjug-” (with various Latin endings) always refers to marriage and nothing else. To the contrary, Casti Connubii contains three uses of “conjug-” referring to non-marital sexual relations.
4. They claim that sexual relations outside of marriage is less sinful with the use of contraception, than the same acts without contraception.
To the contrary, the greater the moral disorder, the greater the sin. Fornication with contraception is more gravely disordered and therefore more sinful. Two wrongs do not combine to make one lesser wrong.
5. The above rejections of the teaching of Humanae Vitae on contraception and abortion imply a rejection of the teachings of Veritatis Splendor on intrinsically evil acts. Since contraception and abortion are each intrinsically evil and always gravely immoral, they cannot be justified by the lack of the marital state, or by a medical intention, or in any other way. Intrinsically evil acts are immoral regardless of intention or circumstances.
So the radical reinterpretation of Humanae Vitae, being proposed by many different conservative authors, is part of two larger problems. The first is the rejection of the dogma of intrinsically evil acts, so that various explanations and rationalizations are used to approve of the more popular intrinsically evil acts, such as lying, contraception, abortifacients, and sexual sins.
6. The second problem is the replacement of the Magisterium with the majority opinion in the conservative Catholic subculture. In this paradigm, teachings are viewed only through the popular explanation, which often involves radical reinterpretation. The result is approval for every type of popular grave sin. The actual teaching of the Magisterium is replaced with whatever interpretation or explanation is given by leaders in the conservative Catholic subculture.
This problem is also seen in the conflict between conservative Catholics and Pope Francis. His magisterial teaching carries no weight, unless it is approved by them. If they find any fault with his words, they feel free to utterly reject and obstinately oppose his every decision.
7. Humanae Vitae teaches that each and every marital act must be unitive and procreative. This implies a rejection of the use of unnatural sexual acts in marriage, for any purpose, at any time. But in keeping with their rejection of magisterial teaching on intrinsically evil acts, many conservatives approve of unnatural sexual acts in marriage. These acts are inherently non-procreative and inherently non-unitive. Therefore, they are intrinsically evil and always gravely immoral.
Many conservative Catholics praise Humanae Vitae, while distorting or rejecting all of its fundamental teachings.
“this people have drawn near to me only with their mouth, and their lips glorify me while their heart is far from me” (Isaiah 29:13).
Humanae Vitae began with a rejection of its teaching by liberal theologians and priests. And now, so many years later, conservatives have joined liberals in rejecting Humanae Vitae. The only difference is that conservatives pretend to accept its teaching, while liberals openly reject its teachings.
 July 31st, 1968; “Catholic Experts In Strong Dissent On Edict By Pope”, New York Times, page 1; continued on page 16.
 Dignitas Personae, n. 23.
 Statement On The So-Called “Morning-After Pill”
 Responses To Questions Concerning Sterilization In Catholic Hospitals
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