Objection: How can you say that the only motive that can excuse the marital act is the procreation of children? It is not against the Natural Law or the Law of the Church to excuse intercourse for the sake of pleasure, health, or love. You are wrong when you say that one must perform the marital act for the purpose or motive of begetting children, and that the procreation of children is the only primary purpose or motive that a couple can use to excuse the marital act. There are many primary purposes or motives of marriage that excuse the marital act from being sinful. One can perform the marital act for many primary reasons such as for the sole purpose or motive of health, satisfying the fleshly lust, quenching concupiscence, mutual help, paying the marital debt, as well as for cultivating mutual love and unitive purposes. Any one of these purposes or motives are enough to perform the marital act in a lawful way, and this proves that spouses can perform sexual acts that are not intended or able to procreate in themselves.
Not so, since the Church and Pope Pius XI, as we have seen, teaches that the primary end or motive of the marital sexual act is the procreation of children, while he describes the other ends or motives of the marital act (if spouses choose to perform the act for these reasons) as secondary ends or motives that are not necessary for the act to be lawful and that are dependent on and which must follow the primary motive of procreation in order for the sexual act to be lawful. The teaching of the Natural Law as well as that of the Church is clear that “the conjugal act is destined primarily by nature for the begetting of children” (Pope Pius XI, Casti Connubii #54) and this is also why Pope Pius XI teaches that spouses are not forbidden to consider the secondary ends of marriage “such as mutual aid, the cultivating of mutual love [unitive purpose], and the quieting of concupiscence... so long as they are subordinated to the primary end [that is, procreation of children] and so long as the intrinsic nature of the act is preserved.” This proves that all other motives than the procreation of children are secondary ends or motives.
Pope Pius XI, Casti Connubii (# 59), Dec. 31, 1930: “For in matrimony as well as in the use of the matrimonial right there are also secondary ends, such as mutual aid, the cultivating of mutual love, and the quieting of concupiscence which husband and wife are not forbidden to consider SO LONG AS THEY ARE SUBORDINATED TO THE PRIMARY END [that is, Procreation of children]and so long as the intrinsic nature of the act is preserved [that is, all sexual acts must be able to procreate in themselves, which means that no unnatural and non-procreative form of a sexual act can ever be performed without sin].”
This means that the primary end or purpose of procreation (in thought and action) can not be made subordinate or subject to the secondary ends or purposes and that the primary end must always exist for the marital act to be lawful while the secondary ends or motives are not needed at all in order to lawfully perform the marital act. The secondary ends “such as mutual aid, the cultivation of mutual love, [unitive purpose] and the quieting of concupiscence” can follow after the primary end or purpose of begetting children if the spouses choose this, but the secondary ends or motives are not absolutely needed to lawfully perform the marital act in the same way as the primary purpose of begetting children, nor is the secondary motive of quieting concupiscence meritorious even though it is allowed. This is also exactly how Our Lord Jesus Christ in the Bible wants us to view the sexual pleasure and the marital act, since it is a higher calling to live for the Spirit than for our own selfish and fleshly desires. “And now, Lord, thou knowest, that not for fleshly lust do I take my sister to wife, but only for the love of posterity, [children] in which thy name may be blessed for ever and ever.” (The Holy Bible, Tobias 8:9)
While some have erroneously asserted that the motive of paying the marital debt to one’s spouse can be used as a primary motive to excuse the marital act from sin, we see that Pope Pius XI defines the paying of the marital debt as a secondary end or motive, by using the words “mutual aid” to explain its nature, since according to God’s Law and Saint Paul in the Holy Bible, a spouse must help his or her spouse by paying the marital debt when the other spouse asks for it in order to not allow the requesting spouse to become tempted to fall into sins of sensuality (1 Corinthians 7).
Many other heretics of our own times also claim that the “unitive” purpose is a primary motive of the marital act along with the motive of procreation, but we can see that Pope Pius XI relegates the unitive purpose, which he calls “the cultivating of mutual love”, to a secondary purpose that are not necessary to exist in order for the act to be lawful.
In fact, the modern day proposition that health, pleasure or love might be the sole object of intercourse is a heresy that has no biblical, apostolic, patristic or medieval authority whatsoever. St. Thomas Aquinas explains in his Summa that: “Although it is not evil in itself to intend to keep oneself in good health, this intention becomes evil, if one intend health by means of something that is not naturally ordained for that purpose; for instance if one sought only bodily health by the sacrament of baptism, and the same applies to the marriage act in the question at issue.” (Summa Theologica, Supplement, Q. 49, Art. 5, Reply to Objection 4)
The Holy Bible confirms the fact that God wants spouses to perform the marital act for the only purpose of procreation. The holy youth Tobias was commanded by almighty God through the Archangel Raphael to never perform the marital act for the sake of lust and that he shall be “moved rather for love of children than for lust,” so “that in the seed of Abraham” he “mayest obtain a blessing in children”. Tobias who was a holy and virtuous person consented to this admonishment by the holy angel and answered God in his prayer that “not for fleshly lust do I take my sister to wife, but only for the love of posterity”.
The Holy Bible, Tobias 6:22; 8:9 “And when the third night is past, thou shalt take the virgin with the fear of the Lord, moved rather for love of children than for lust, that in the seed of Abraham thou mayest obtain a blessing in children… [Tobias said:] And now, Lord, thou knowest, that not for fleshly lust do I take my sister to wife, but only for the love of posterity, in which thy name may be blessed for ever and ever.”
The holy youth Tobias approached his bride Sara after three days of prayer, not for fleshly lust but only for the love of posterity, having been instructed by the Archangel Raphael that to engage in the marital act he shall “be moved rather for love of children than for lust”.
According to God’s will, spouses are to engage in the marital act for the “love of posterity” (children), not for lust. No, contrary to what most people today say, the Holy Bible is clear that spouses are to come together “only for the love of posterity” if they want to please Our Lord Jesus Christ. The Holy Word of God in the Bible is indeed true when it says that “the devil has power” over all spouses who come together for the purpose of gratifying their fleshly pleasures, giving “themselves to their lust, as the horse and mule, which have not understanding”.
Tobias 6:16-17 “Then the angel Raphael said to him [Tobias]: Hear me, and I will show thee who they are, over whom the devil can prevail. For they who in such manner receive matrimony, as to shut out God from themselves, and from their mind, and to give themselves to their lust, as the horse and mule, which have not understanding,over them the devil hath power.”
It is a divine law, a dogma of the faith (de fide), that the primary end of marriage is procreation (bearing children) and the education of children. Pope Pius XI decrees it “is beyond the power of any human law” to teach otherwise.
Pope Pius XI, Casti Connubii (# 8), Dec. 31, 1930: “To take away from man the natural and primeval right of marriage, to circumscribe in any way the principal ends of marriage laid down in the beginning by God Himself in the words ‘Increase and multiply,’ is beyond the power of any human law. … This is also expressed succinctly in the  Code of Canon Law [Canon 1013]: ‘The primary end [or purpose] of marriage is the procreation and the education of children.’”
A Practical Commentary on Canon 1013 explains that: “there can be no controversy over the primary object of marriage. The perpetuation of the human race is willed by the Creator, who from the creation of mankind appointed the means for this purpose… The Holy Office condemned the opinion defended by some recent authors who deny that the procreation of children is the primary end of matrimony, and regard its secondary ends not subordinate to its primary end but independent of it.” (April 1, 1944; Acta Ap. Sedis, XXXVI, 103.)
It could not be more clear from both the Natural Law as well as the teachings of the Church that: “The primary purpose of marriage is the procreation and education of children.” (The 1917 Code of Canon Law, Canon 1013) Therefore, it is heresy to teach that procreation and education of children is not the only primary end of marriage.
Objection: The Bible doesn’t condemn birth control. Modern birth control methods were unknown in Bible times, and the Bible is, therefore, silent on the matter. The closest that Scripture comes to condemning birth control is Genesis chapter 38, the account of Judah’s sons Er and Onan. Onan’s motivation was selfish; he used Tamar for his own pleasure, but refused to perform his legal duty (from Deuteronomy 25:5-10) of creating an heir for his deceased brother. This passage (in Genesis 38) is often used as evidence that God does not approve of birth control. However, it was not the act of contraception that caused the Lord to put Onan to death as you say; it was Onan’s selfish motives behind the action. God did not kill Onan for practicing contraception but because he refused to obey the Law from Deuteronomy 25:5-10 that instructed brothers to raise up seed for his dead brother. This fact proves that God doesn’t directly condemn contraception in the Bible. Contraception, by definition, is merely the opposite of conception. It is not the use of contraception that is wrong or right. As we learned from Onan, it is the motivation behind the contraception that determines if it is right or wrong. Ultimately, a couple’s motives for delaying childbearing, using contraception, or even having numerous children, are between them and God. Therefore, we can find no biblical admonition against the use of birth control in and of itself.
Answer: God’s law in the Old Testament did not even command the death penalty for the person who refused to create heirs to his deceased brother. The brother who refused this duty was, as a punishment, only to be publicly disgraced!
Deuteronomy 25:5-10 “When brethren dwell together, and one of them dieth without children, the wife of the deceased shall not marry to another: but his brother shall take her, and raise up seed for his brother: And the first son he shall have of her, he shall call by his name, that his name be not abolished out of Israel. But if he will not take his brother’s wife, who by law belongeth to him, the woman shall go to the gate of the city, and call upon the ancients, and say: My husband’s brother refuseth to raise up his brother’s name in Israel: and will not take me to wife. And they shall cause him to be sent for forthwith, and shall ask him. If he answer: I will not take her to wife: The woman shall come to him before the ancients, and shall take off his shoe from his foot, and spit in his face, and say: So shall it be done to the man, that will not build up his brother’s house: And his name shall be called in Israel, The house of the unshod.”
This bible verse shows us that disobeying the Law of the Old Testament that directed a man to marry his dead brother’s wife in order to raise up seed for his brother, was not something that was a particularly serious infraction in the eyes of the Lord, for if God would have considered this act of disobedience as a great crime, He would have instituted a punishment that was much more severe than being only a little disgraced or mocked, which almost is no punishment at all.
According to The Book of Genesis, the reason for why Onan was killed was because: “He knowing that the children should not be his, when he went in to his brother’s wife, spilled his seed upon the ground, lest children should be born in his brother’s name.” Notice how clearly this biblical text shows that the reason Onan did this “detestable thing” was “lest children should be born in his brother’s name”, thus showing us that the act of performing the marital act while taking steps to hinder procreation is hated by God. This absolutely proves that a person who performs the marital sexual act with an intention opposed to procreation – is condemned according to God’s Holy Law.
Genesis 38:8-10 “Juda, therefore said to Onan his son: ‘Go in to thy brother’s wife and marry her, that thou mayst raise seed to thy brother.’ He knowing that the children should not be his, when he went in to his brother’s wife, spilled his seed upon the ground, lest children should be born in his brother’s name. And therefore the Lord slew him, because he did a detestable thing.”
Therefore, it is abundantly clear from the Bible itself that Onan was not killed for his deed of refusing to fulfill his duty to create heirs for his deceased brother, as the protestants claim, since this act was only punished with a public disgrace (Deuteronomy 25:5-10). What deed then was Onan killed for? Obviously, he was killed for the wicked and selfish deed of having sexual relations while practicing contraception; and for being against conception. Truly, if Onan did not want to raise up heirs for his deceased brother, he should not have had sexual relations with her while pretending to fulfill the marital duty of procreating children (even though he did not); and obviously, he must not practice coitus interruptus while selfishly indulging in the sex act, since this is an act against nature.
God did not even ordain for a man to die or even be hurt if he refused to raise up seed for his deceased brother according to the Old Testament Law, but when Onan performed the actual marital sexual act without wishing to beget children, God instantly killed him in order to show us the hatred God have of those who do not excuse the marital sexual act with the absolutely necessary motive of procreation. Thus, the refusal to not raise up children for one’s brother is not a very grave crime in the eyes of God as long as one does not perform the marital act, but performing the marital sexual act without wanting to have children is a very grave crime according to God’s Holy Law. Since God foresaw the great evil and selfishness of many in the future (and especially in our own time) who were to practice contraceptive sexual acts, and in order to help future generations of Jews and Christians to abstain from all contraceptive acts: it is clear that God killed Onan to set an example for future generations.
Since God utterly detests the act of contraception, God also sometimes allows the evil demons who incite men and women to commit this act, to kill them when they consent to their temptations, as is recorded in the Book of Tobit, where the seven husbands of Sarah was killed; since they tried to perform the marital act for selfish and lustful reasons. As in the case from Tobit, it seems clear that since Onan wanted to selfishly and lustfully enjoy the sex act without intending having children, as God’s holy law requires, that a demon, or the evil angel Asmodeus that kills lustful and wicked people, was permitted by God to slay him (cf. Tobias 3:8). Haydock commentary explains: “[Genesis 38] Ver. 10. Slew him, perhaps by the hand of evil angels, Psalm lxxvii. 49. Asmodeus, &c., who slew the libidinous husbands of Sara. (Tobias iii. 7.) (Menochius)”
The design of this institution of raising up seed for a brother – which was not originated by Moses, but came down from early times (Genesis 38:8) and is to be found amongst other nations than the Jews, and that even in the present day – was to preserve a family from becoming extinct and to secure the property of a family from passing into the hands of a stranger.
Thus, the claim that “it was not the act of contraception that caused the Lord to put Onan to death; it was Onan’s selfish motives behind the action” is of course ludicrous and false, and is easily refuted not only from the Bible itself as we have seen, but also from the writings of the Fathers. We will quote only St. Augustine:
“As St. Augustine notes, ‘Intercourse even with one’s legitimate wife is unlawful and wicked where the conception of offspring is prevented.Onan, the son of Judah, did this and the Lord killed him for it (Gen. 38:8-10).’” (Pope Pius XI, Casti Connubii # 55; St. Augustine, De Conjugiis Adulterinis, Book II, Chapter 12)
Furthermore, this objection of excusing contraception is also condemned by the Holy Word of God in both an explicit and implicit way. Indeed, the Bible does have quite a lot to say about children. The Bible presents children as a gift from God (Genesis 4:1; Genesis 33:5), a heritage from the Lord (Psalm 127:3-5), a blessing from God (Luke 1:42), and a crown to the aged (Proverbs 17:6). God sometimes blesses barren women with children (Psalm 113:9; Genesis 21:1-3; 25:21-22; 30:1-2; 1 Samuel 1:6-8; Luke 1:7, 24-25). God forms children in the womb (Psalm 139:13-16). God knows children before their birth (Jeremiah 1:5; Galatians 1:15).
It’s not a couple that decides for themselves whether God should send them new life or not as the biblical verses already provided proves, but this is wholly up to God and His holy will (Matthew 6:10).
Genesis 30:1-2 “And Rachel seeing herself without children, envied her sister, and said to her husband: ‘Give me children, otherwise I shall die.’ And Jacob being angry with her, answered: ‘Am I as God, who hath deprived thee of the fruit of thy womb?’”
We all know that God is the One who opens the womb, the One who killeth and maketh alive. “The Lord also remembering Rachel, heard her, and opened her womb.” (Genesis 30:22) In truth, “The Lord killeth and maketh alive, he bringeth down to hell, and bringeth back again.” (1 Kings 2:6)
So why would a woman who desires to fulfill the will of God make a systematic effort to avoid God sending her a new life? What excuse could such a person possibly make for going out of her way to calculate how to have marital relations without getting pregnant with the child God was going to send? Why would a woman (or a man) who believes that God opens the womb try to avoid His opening of the womb by a meticulous and organized effort, involving birth control methods, charts, cycles or thermometers? The answer is that those who engage in such behavior as contraception selfishly turn from God (which is the essence of sin) and refuse to be open to His will.
God, and not man, is the only one that can lawfully decide whether a couple shall receive a child or not. Can you imagine what Jacob would have said to Rachel if she had discovered a new way to avoid “the Lord opening her womb?” He would probably have rebuked her as an infidel.
Objection: Natural Family Planning is a justifiable practice of birth control because it does nothing to obstruct the natural power of procreation.