Lesson 30: The Sins Against Marriage


"But for fear of fornication, let every man have his own wife, and let every woman have her own husband.  Let the husband render the debt to his wife, and the wife also in like manner to the husband.  The wife hath not power of her own body, but the husband.  And in like manner the husband also hath not power of his own body, but the wife.  Defraud not one another, except, perhaps, by consent, for a time, that you may give yourselves to prayer; and return together again, lest Satan tempt you for you incontinency."  (1 Corinthians 7:2-5)


"And the Pharisees coming to Him asked Him:  'Is it lawful for a man to put away his wife?' tempting him.  But he answering, saith to them:  'What did Moses command you?'  Who said:  'Moses permitted to write a bill of divorce, and to put her away.'  To whom Jesus answering, said:  'Because of the hardness of your heart he wrote you that precept.  But from the beginning of the creation, God made them male and female.  For this cause a man shall leave his father and mother; and shall cleave to his wife.  And they two shall be in one flesh.  Therefore now they are not two, but one flesh.  What therefore God hath joined together, let not man put asunder.'  And in the house again His disciples asked Him concerning the same thing.  And He saith to them:  'Whosoever shall put away his wife and marry another, committeth adultery against her.  And if the wife shall put away her husband, and be married to another, she committeth adultery."  (Mark 10:2-12)


"Juda therefore said to Onan his son:  'Go in to thy [deceased] 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."  (Genesis 38:8-10)

  1. What are the sins against marriage?

    1. Refusing the marriage debt.
    2. Unlawful separation.
    3. Divorce.
    4. Sinful company keeping.
    5. Adultery.
    6. Birth control.
    7. Abortion.
    8. Sterilization.

  2. What is the marriage debt?

  3.    The "marriage debt" means that a married person is obliged, under penalty of mortal sin, to give his (or her) married partner sexual intercourse whenever it is reasonably asked for.
    Lawful excuses for refusing:  Adultery, sickness, drunkenness, insanity, non-support, danger to an unborn baby.

  4. Should a married person always insist on the right to intercourse?

  5.    No, because a marriage cannot be successful unless it is founded on love and unselfishness.

  6. Why is it a mortal sin to separate from your partner?

  7.    Separation in a valid marriage is a mortal sin because --
    1. God said so.
    2. To separate means to refuse the marriage debt (mortal sin).
    3. A separated person is tempted to commit adultery or some other sin.
    4. Children cannot be properly trained.

  8. Is a validly married person ever allowed to separate from his (her) spouse?

  9.    Yes, but only for a very serious reason, and only with permission of the bishop.

  10. Why is divorce and remarriage a mortal sin?

  11.    Because it is clearly against the law of God.
    "Every one that putteth away his wife, and marrieth another, committeth adultery:  and he that marrieth her that is put away from her husband, committeth adultery."    (Luke 16:18)

    "A woman is bound by the law as long as her husband liveth; but if her husband die, she is at liberty:  let her marry to whom she will; only in the Lord."    (1 Corinthians 7:39)

  12. May a separated or divorced person keep company with another?

  13.    No, not if the marriage is valid, because such a person is still married, and a married person is never allowed to keep company with another.
    "Therefore while her husband liveth, she shall be called an adulteress, if she be with another man."    (Romans 7:3)

  14. What is adultery?

  15.    Sexual intercourse between a married person and someone to whom he (or she) is not married.

  16. What is the sin of birth control?

  17.    Doing anything before, during or after intercourse to keep the woman from becoming pregnant.
    "Marriage honorable in all, and the marriage bed undefiled."    (Hebrews 13:4)

    "He [Onan]...when he went in to his [deceased] 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."    (Genesis 38:9-10)

  18. Is birth control ever allowed by God?

  19.    No, it is always a mortal sin.
    "He [Onan]...when he went in to his [deceased] 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."    (Genesis 38:9-10)

  20. What is the sin of abortion?

  21.    Killing an unborn baby.
    "Thou shalt not kill."  (The Fifth Commandment)

  22. Is abortion ever allowed to save a mother's life?

  23.    No, because to take away the life of any innocent human being, even that of an unborn human being, is always murder.
    From just the medical point of view, abortion is not the safe and simple procedure it is made out to be.  It can cause serious injury to the woman, and even death.  Women who have had abortions become sterile and miscarry more often than those who have not, plus abortion leads more often to tubal pregnancies than in women who have not aborted their children.  Doctors concede that it is always safer for the woman to come to term with her pregnancy than to have an abortion, even if this means having a caesarian section.

  24. What happens to a Catholic who knowingly has an abortion?

  25.    Automatic excommunication is the penalty for this crime.
    This means that such a person cannot receive the Sacraments nor have a Catholic funeral.

  26. Can an excommunicated person get back into the Church?

  27.    Yes, if he is truly sorry for having committed the crime.
    However, the priest who hears his confession has to get special power from the bishop to take away the excommunication.

  28. What is sterilization?

  29.    Making the reproductive organs unfruitful, usually by tying or cutting the fallopian tubes, cutting or tying the seminal vesicles (vasectomy), or removing the ovaries or uterus (hysterectomy).

  30. What kind of sin is sterilization?

  31.    Always a mortal sin, unless the organs are diseased and must be removed because they are a danger to the health of the whole body.
    A woman is never allowed to have her tubes tied nor a man allowed to have a vasectomy under any conditions, even under doctors' orders.  If there is serious danger to the woman's life or health, the only solution in accord with God's law is to refrain from sexual intercourse totally or periodically.


  1. The sins discussed in this lesson are against the law of God and are therefore forbidden to everyone, not just to Catholics.
  2. If lack of money or poor health make it difficult for you have children, consider that this is the cross Jesus wants you to carry and that He will give you the strength to carry it.
  3. Expectant mothers should be careful about signing papers in the hospital; they should not consent to a D & C unless it is certain the baby is already dead.
  4. Women having abdominal operations should also tell the doctor not to tie the tubes.  (A woman who has had her tubes tied is not required to have them untied.  However, to do so is praiseworthy and proves the woman has true contrition for having had her tubes tied.)
  5. Birth control pills often work by causing early abortion.  The IUD is an abortifacient also.