NFP and Natural Law

Dear Grace,
I have a question about NFP and the natural law. I understand that God made marriage for two inseparable purposes, to be unitive and procreative. Based upon that premise, I am assuming the following:

First, intercourse with NFP, knowing that there will be no conception, satisfies the natural law of God. Second, intercourse with artificial contraception, knowing that there will be no conception, does not satisfy the natural law of God. Is my understanding correct?

Grace answers: On a basic level, your understanding is correct, but it needs some clarification. You are right that God made marriage for two purposes: to be unitive (uniting the spouses in love) and to be procreative (to bear children, if and when it was His divine will). These two purposes are inseparably connected in marriage, and man and woman can do nothing to break this connection, for to do so would go directly contrary to the plan of the God (CCC# 2366). How is this connected to the natural law?

If we accept that God has a plan of salvation for all mankind, then it makes sense that when He creates every human person, He instills within that person all that is necessary to attain that salvation. Each one of us is on a journey back to the One who created us. That is our eternal destiny. On this journey, however, we have the freedom to make the choices in our lives that will lead us either away from or towards that destiny. Thus, deep within, God instills in us what is called the natural law.

In his Encyclical Veritatis Splendor (The Splendor of Truth), John Paul II quotes from the Second Vatican Council and Scripture: “In the depths of his conscience man detects a law which he does not impose on himself, but which holds him to obedience. For man has in his heart a law written by God. To obey it is the very dignity of man; according to it he will be judged” (cf. Rom 2:14-16; VS, n. 54). Pope Paul VI also reminds us that, “the natural law declares the will of God, and its faithful observance is necessary for man's eternal salvation (Humanae Vitae, 4).

Your understanding of the difference between the use of artificial contraception and NFP (Natural Family Planning) is technically correct, but the words used are not exactly the best. You speak in terms of two ways to have intercourse, one that “satisfies” the natural law of God and one that does not. Rather than use the word “satisfies” it would be best to think in terms of listening to and obeying that “light of understanding infused in us by God, whereby we understand what must be done and what must be avoided” (VS, n. 12).

When a couple practices NFP to avoid pregnancy, they will not have intercourse during fertile periods. Keep in mind, of course, that NFP can be and is used also by infertile couples as a method to help them conceive a child. So often today when we speak of NFP it is assumed that the purpose is to avoid pregnancy. And we also fail at times to recognize the wonderful benefits for the married life of the couple that practices NFP. NFP calls for a mutual responsibility on the part of both husband and wife and this brings about a deeper communication between them and a profound respect for each other. In NFP both spouses come to understand the nature of fertility and they learn how to work with it, either to plan or avoid a pregnancy. In learning that they have a shared responsibility for planning their family, husbands are encouraged to understand their wives' reproductive cycles and both spouses begin to realize the value of speaking openly and frankly about their sexual desires and also the particular circumstances of their family that may have impact on its size.

When the purpose of a husband and wife is to not conceive a child and they are using NFP, then when they do have sex, it will unite them in love by bringing them closer together because they will give themselves totally to each other when their marital act is open to life. In other words, it will not separate the two purposes of God for marriage. Their marital acts will be both unitive and procreative, because the possibility to conceive still exists. If they use artificial birth control, however, they will have intercourse, but the two purposes of marriage will be separated because their act will not be open to life and also because what should be a total gift of self will be a lie. They are not giving themselves totally, but instead they are holding something back.

Another factor to keep in mind is that NFP, like artificial contraception, can sometimes also be practiced for selfish reasons. This is one very crucial reason why couples need to think and consider well if they are indeed prepared for the responsibilities of marriage before entering into this covenant with each other and God. They must remember that when they decide to marry in the Lord, they make a total commitment to God as well as each other. That is, they pledge to love each other without conditions, but also to love God without conditions. The obedience couples owe to God is beautifully expressed and demonstrated in their openness to new life in each and every sexual act. Responsible parenthood “concerns the objective moral order which was established by God, and of which a right conscience is the true interpreter. In a word, the exercise of responsible parenthood requires that husband and wife, keeping a right order of priorities, recognize their own duties toward God, themselves, their families and human society (HV, 10).

No matter what the world tells us, sex was not given for self-gratification or simply to make a partner “feel good.” Yes, of course it is right and good that a married couple should enjoy their shared sexual life, but always keeping in mind that God gave it for the sharing of love and the transmission of life. This is the natural law written in the hearts of men and women.

© Copyright 2004 Grace D. MacKinnon

For permission to reprint this article, or to have Grace speak at your event, contact Grace MacKinnon at

Grace MacKinnon holds an MA in theology and is a syndicated columnist and public speaker on Catholic doctrine. Her new book Dear Grace: Answers to Questions About the Faith is available in our online store. If you enjoy reading Grace’s column, you will certainly want to have this book, which is a collection of the first two years of “Dear Grace.” Faith questions may be sent to Grace via e-mail at: You may also visit her online at

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