Strictly speaking, NFP is not “right.” It is neutral. Used judiciously, it is acceptable for the couple. As Alyosha13 said in the opening post, it can be abused if the couple use it unjustly. Even when abused, the action of NFP is nothing. Because a couple using NFP does nothing there is never an objective moral wrong committed.
But this is an incorrect argument, both in theory, and in practice. OF COURSE the couple takes an action. They learn about NFP. They change the frequency and timing of the marital act from fertile periods to infertile periods. Just from the letters in these forums alone, that is often an unbearable burden.
But seriously, if people weren’t acting on NFP then NFP WOULDN’T EXIST. The argument that the couple is doing nothing simply makes no sense.
Contraception, however, is always an abuse of the Creator’s design.
Why?
Is a car an abuse of the Creator’s design for our legs? Bad analogy? How about rollerskates? Shoes?
Even when they have serious reasons to avoid pregnancy for a time, a couple actively works against God when they resort to it.
I’m sorry, EXACTLY THE SAME argument can be made for NFP+abstinence. A couple ACTIVELY TIMES their marital act to occur when an egg cannot be fertilized.
Contraception therefore is an objective moral wrong even if the motives are otherwise acceptable.
In which case I guess we can also argue that a car, rollerskates and penicillin also work actively against God when we resort to them?
God created us. He created our minds and our hands and commanded us to use them. He gave us dominion over the Earth. The intention of spacing children is not wrong and is the same for NFP or ABC. The argument that NFP and ABC are different (ignoring for discussion sake that some forms of ABC might have abortifacient side-effects) is, based on the arguments presented so far, not a strong one.
There are, indeed, 2 levels in discussion here: the act and the motive. It is impossible for us humans to judge the motive. God alone can do that.
However, it is possible for us to judge the act. Certain things we know about. We know murder is wrong because it is explicitly condemned in the Bible. Contraception is not explicitly addressed in the Bible but it has been explicitly, consistently addressed by the Church. Jesus assured us that the Church would be guided by the Holy Spirit. Therefore we can be confident that what she teaches is true.
The Church has a history of incorrectly addressing issues that have a scientific basis. Therefore, given that there is much of a scientific/medical nature learned about human sexuality in the last 150 years, and accelerating in the lat 80, 60, 40… it is, frankly, quite easy to believe that the past arguments provided by the Church are based on historical and traditional biases of mankind, and generally incorrect medical and scientific information. Perhaps there is a good argument that the past decisions made sense in their day; it is highly difficult to not question these arguments today - and find them wanting.
The Church also has a history of being slow admitting such errors. It was what - 380 years before they issued an apology with respect to Galileo?
Everything He does follows his moral and physical laws. Science helps us to come to know him by studying and learning in depth His physical laws. I do not believe that God breaks His physical laws any more than I believe that He breaks his moral laws. If He did, His universe would be random. If His universe were random, then his commandment that we love him with all our heart, and soul, and strength and mind would be at best meaningless, and at worst mischievous or even malicious. God is not these things.
In learning about His physical laws, we can sometimes learn more about His moral laws. There would have been a time, no doubt, that an effective scientific/medical technique like a blood transfusion would have been abhorrent for a host of religious reasons. (1669, in fact)
In some ways this is a good analogy, because in earlier times, people believed there was a life force in blood, as they also believed there was in semen.
In 1669 the Vatican prohibited blood transfusions. I have been unable to document when that was first reversed; but sometimes, things do change.