As a Catholic, I know that use of contraceptives is immoral. I understand that, in their use, I am keeping God out of the procreative act. How is it that use of Natural Family Planning (NFP) is approved to postpone preganancy in a valid marriage? I have friends who are saying “Natural Family Planning is just a Catholic way of contracepting.”
For just reasons, postponing the start of a family or planning the spacing of children, which is what both artificial contraceptives and NFP allow, is not intrinsically immoral. Assuming that the postponement and/or spacing is not done for selfish reasons, prudentially planning one’s family may be meritorious. What is intrinisically immoral is indulging in relations but frustrating their natural consequences: artificial contraceptives allow a couple to do this; NFP does not.
So, what we have here is a possibly good goal (using prudential judgment to plan one’s family) with two possible means: artificial contraception and Natural Family Planning. Analogously, a person can have the good goal of supporting his family and two possible means: robbing banks or honest labor. As one cannot use the good goal of supporting his family to justify robbing banks, so one cannot use the possibly good goal of planning one’s family to justify indulging in relations while excluding their natural consequence of children.
God, Sex, & Babies: What the Church Really Teaches about Responsible Parenthood by Christopher West