When Is It Sinful to Use Natural Family Planning (NFP)?

Overview

Explore when using Natural Family Planning becomes sinful, and learn the moral distinctions between venial and mortal sin in Catholic teaching.

When Is it Sinful to Practice Natural Family Planning? And Would it be Mortally Sinful or Venially Sinful? 

In many parishes, Natural Family Planning is spoken of simply as “the Catholic option” for spacing children. While this much is true, it often leaves couples without a clear understanding of why the Church allows NFP and under what conditions its use is morally permissible. Moreover, many are led to think that if those conditions are not met, then NFP would be a mortal sin essentially no different from contraception itself. In light of these confusions, in this article we will explore how the differences between natural family planning and contraception can enable us to be more precise about when natural family planning is permissible, when it is sinful, and when sinful, when it would be venially sinful or mortally sinful.

The Difference Between Contraception and Natural Family Planning

We will be rolling out an article entirely devoted to the precise way in which contraception differs from NFP, but for the sake of brevity, suffice it to say that in contraception there is in the exercise of the marriage act an added countermeasure to frustrate the procreative element of the marriage act. This is simply not the case with recourse to natural family planning. In natural family planning, the ontological integrity of the marriage act in its fecundity is not through a deliberate countermeasure actively frustrated in its capacity to transmit life; rather, a mere abstention is opted for in a way that keeps the natural fecundity of the marriage act in tact but serves an abstracted intention simply to not have a baby. That intention of not having a baby is not what constitutes the sin of contraception, it is in the added countermeasure which frustrates the fecundity of the marriage act which constitutes the sin of contraception. So long as this added countermeasure against fecundity is not chosen either through some barrier method or through artificial means, whatever else may be said about family planning, it is not contraceptive. This naturally leads to the central question of this article: what are the conditions that must be met in order for Natural Family Planning to be entirely free from sin altogether? Given how NFP is talked about today in contemporary parish life, it may seem on the face of it strange to speak as though it even needs qualifying conditions in order to free it from any sin. If the ends of sexuality are respected and the fecundity of the marriage is not impeded, shouldn’t a couple be able to have recourse to NFP whenever they see fit? Could it truly cost them their salvation even if they are avoiding contraception? 

Sinful Use of NFP? Is it Venial or Mortal?

In order to deal with this question, I want to say from the outset that due in large part to the abandonment of manualism in moral theology, there has been less precision and care in distinguishing between mortal sin and venial sin in classifications of actions that admit of slight matter. Unfortunately, this can lead to confusion and unintentionally aid and abet the scourge of scrupulosity, for while both mortal sin and venial sin must be avoided, the urgency with which each must be avoided is unmistakably wildly different. This tendency has sadly affected how the moral preconditions for licit use of natural family planning are talked about, as if to suggest that either NFP is done virtuously or in a way that costs each spouse their eternal salvation. This is far too simplistic, and moreover, spiritually perilous when the moral preconditions for licit use of NFP have themselves not been spelled out with sufficient clarity. In pursuit of clarity, then, let me frame the discussion of those moral preconditions within this general principle about categorizing the gravity of sexual sin within marriage. Virtually all moralists of the last century and a half have agreed that, apart from adultery, the only grave sexual sins that spouses can commit together are acts which either impede procreation or violate conjugal justice or love. Sins that impede procreation would include contraception and voluntary pollution. Sins that violate conjugal justice or love would include unjustly refusing to render the marriage debt,  knowingly and willingly treating the spouse as nothing more than an outlet for sexual pleasure, willingly harboring contempt for the ends of marriage, or marital rape. Therefore, it can be safely held that, since natural family planning is not the same act as contraception, the only instance where it would be mortally sinful is if it involved an indefinite and absolute refusal to realize the fecundity of marriage in the total absence of any justifying reason other than a contempt for childbearing. 

Short of this, any use of natural family planning outside the four serious reasons provided for by the Popes which excuse sin altogether (i.e., financial, medical, social, or psychological) would, it seems to me, not exceed venial guilt. Let’s briefly examine each of these reasons to attain further clarity on when use of NFP constitutes no sin at all. All of these four reasons are reducible to the same principle: if financial constraints, medical complications, social upheaval or breakdown, or psychological conditions render it an undue burden for parents to provide either for their own welfare or for the welfare of their children, then NFP can safely be used without any sin whatsoever. In fact, they would not merely be avoiding sin, but would be practicing the virtue of prudence!