There is a very high level of confusion among Catholics regarding the abortifacient action of various forms of birth control. Unfortunately, this uncertainty is actively promoted by the very profession that should be trying to clarify health issues to the public.
The modern medical profession acknowledged for decades that the beginning of pregnancy was the fusion of sperm and egg ― indeed, this is the only logical point for the beginning of human life. In fact, most embryology and fetology textbooks still emphasize that the beginning of human life is at fertilization.
However, in the early 1960s, the American Medical Association led the movement to redefine the beginning of “pregnancy” from fertilization to implantation. There was absolutely no scientific or medical reason to do this, and the AMA never offered any explanation for this change. But the medical profession knew that abortifacient pills and IUDs were on the way, and so changed this fundamental definition in order to pave the way for these new drugs and devices, thus employing a medical version of the Supreme Court’s “raw exercise of power” that would legalize abortion a decade later. From the viewpoint of the family planners, a welcome side effect was to soothe the consciences of women who would accept methods of true barrier contraception, but not even the earliest abortion.
All of this misinformation has led to a curious state of mind in many Catholic women and men. They suspect that the true mode of action of the birth control they are using might be abortifacient, but they do not want confirmation that it indeed acts in this manner. In this way, they can remain what we call “willfully ignorant.” Unfortunately, this mindset is also found among some Catholics, who have a psychological investment in staying ignorant. Giving up the Pill or other form of birth control would lead to confronting difficult decisions and lifestyle changes, which indicates the presence of a deadly type of spiritual sloth.
For pro-lifers, it is the worst kind of hypocrisy to swallow a birth control pill every day while vocally opposing surgical abortions. This paradox has been pointed out by a number of leading pro-life Protestant writers. For example, Karen Swallow Prior remarks “I have never understood pro-lifers’ squeamishness at the morning after pill absent the same concern with the daily pill — except perhaps the latter hits a bit closer to home for so many.”
Many or even most Catholics do not believe that using birth control ― either truly contraceptive or abortifacient ― is a mortal sin. They may have never heard the sinfulness of the use of contraception preached from the pulpit. Father Paul Marx, the founder of Human Life International, told me many stories of people approaching him after one of his guest homilies in a parish and telling him that they were entirely unaware of Church teachings on this topic. Other Catholics may sincerely believe the dissenter’s mantra that “conscience is our final guide, even if it conflicts with Church teaching.”
Regardless the reason, every adult Catholic should be aware of the Church’s teachings on both contraception in particular and conscience in general. The maxim “Ignorance of the law is no excuse” certainly applies here. We do not deliberately remain ignorant of traffic law, because we want to avoid accidents and traffic citations. We do not choose to remain ignorant of the rules and regulations at our place of employment, because we want to avoid being fired. And we do not consciously remain ignorant of the effects of various lifestyle choices involving smoking, overeating and exercise, because we want to live longer.
But millions remain profoundly uninformed about Church teachings on sexual ethics, even though the consequences of ignoring them are infinitely worse than traffic tickets or even a long, grinding period of unemployment or sickness.
The ultimate Judge ― Whom we will all one day face ― will certainly not accept the excuse “Sorry, I just didn’t know.”
As St. Jerome said, “Ignorance of the scriptures is ignorance of Christ.” We might add that “Ignorance of Church teachings is ignorance of how to live a holy life.”
At some point, lack of knowledge ceases to become mere ignorance and leads to mortal sin. Like it or not, all Catholics have a duty to know what our Faith teaches about sexual morality, and, if we intend to pursue eternity in Heaven with Our Lord, we have a serious and fundamental duty to follow these teachings conscientiously. There is no “right” to remain culpably ignorant.
As we have seen, all methods of non-contraceptive birth control act to cause early abortions at least some of the time. This means that their use is prohibited by Catholics. But what if the Catholics who use them and encourage or counsel their use are unaware of their abortifacient action?
The commission of a mortal sin requires three elements: The sin itself must be of grave matter, there must be full consent of the will, and the person must have full knowledge of what he or she is doing [Catechism, ¶1858-1859].
On this last point, we must consider whether or not it is a Catholic’s duty to know if their birth control method is abortifacient. More fundamentally, should they be aware that the use of any contraceptive method is mortally sinful?
The Catholic tradition regards use of contraceptives as gravely sinful, regardless of whether they are simple barrier methods or act as true abortifacients. From the standpoint of the Church, the use of either is an equally grave sin, and results in a separation of the person’s soul from God.
This has been the constant teaching of the Church since Her founding. The duty of every Catholic to know Church teachings is equally ancient.
St. Paul told us that ignorance of God is the source of all moral deviations [Romans 1:18-32, CCC 2087]. He also said that the obedience of Faith is our first duty towards God [Romans 1:5, 16:26].
Dissenters often quote the “spirit of Vatican II” while attempting to justify their disobedience. Oddly, they never quote Ad Gentes, which stated that “All Christians, by the example of their lives and the witness of their word, wherever they live, have an obligation to manifest the new man which they have put on in Baptism and to reveal the power of the Holy Spirit by whom they were strengthened at Confirmation” [¶11, CCC 2472]. Dignitatis Humanae taught that “It is in accordance with their dignity that all men, because they are persons … are both impelled by their nature and bound by a moral obligation to seek the truth, especially religious truth. They are also bound to adhere to the truth once they come to know it and direct their whole lives in accordance with the demands of truth” [2§2, CCC 2467].
Father Peter T. MacCarthy concisely summarized our duty when he wrote that “We all have the obligation to verify that our actions are moral, especially in the area of sexuality, where sins always adversely affect others as well as ourselves. Those who use all kinds of psychological mental tricks to avoid knowing the truth are never deceiving God, but only themselves.”
Thus, willful ignorance is an offense against the cardinal virtue of justice, which is giving to God and others what is rightly due to them. The use of contraception primarily violates God’s rights, Who alone opens and shuts the womb, but also trespasses upon the rights of the children who would have otherwise been born. The many women who use contraception without telling their husbands (or the husbands who get a vasectomy without telling their wives) are also grossly violating the rights of their spouses.
Choosing to remain ignorant also leads to a kind of deadly spiritual sloth, which in turn makes it more probable that the person will commit even more serious sins. Germain Grisez wrote that “In general, a person who is willing to do what is wrong and is uncertain because of a doubt of fact how grave that wrong will be, is willing to do the more serious wrong.”
The 1974 Declaration on Procured Abortion states that “From a moral point of view this is certain: even if a doubt existed concerning whether the fruit of conception is already a human person, it is objectively a grave sin to dare to risk murder” [¶13]. The focus of this passage is on the personhood of the embryo, but could also be applied to the abortifacient, or killing effect, of most modern birth control methods.
In summary, then, there is no “right” to remain ignorant in these matters of the moral law. We cannot claim ignorance when dealing with secular authorities, and we will certainly not be able to claim lack of knowledge when we stand in judgment before Jesus Christ. This is particularly true of those many celebrity Catholics who completely disregard their duties and call themselves “devout,” while supporting and promoting such horrors as homosexual “marriage,” abortion and euthanasia.
This principle also applies to rank and file Catholics. No matter how high or low our station in life, we all have a serious obligation to know and practice the truth. We will all be judged equally on how well we carried out this duty.
 Karen Swallow Prior. “The Pill: Contraceptive or Abortifacient?” The Atlantic, December 31, 2012, at http://www.theatlantic.com/sexes/archive/2012/12/the-pill-contraceptive-or-abortifacient/266725/.
 Father Peter T. MacCarthy. “Our Moral Guide.” Homiletic and Pastoral Review, August-September 1988, pages 39 to 42. See the Catechism of the Catholic Church, ¶1782.
 Germain Grisez. The Way of the Lord Jesus. Volume I, “Christian Moral Principles” [Chicago: Franciscan Herald Press], 1983. Chapter 12, Moral Judgment in Problematic Situations, Question B, Paragraph 5. The full text of the entire three-volume work can be found http://www.twotlj.org/.