I wanted to offer my experience being taught NFP as a non-Catholic.

Five years ago, I was a pro-choice, pro-homosexual "rights" atheist  who had had terrible side-effects on the Pill and Depo. A devoutly  Catholic friend loaned me The Art of NFP. When she did, she did not  state that it was written from a "Catholic perspective." (i.e., there was no advance warning that I would be reading Catholic theology!)

My initial motives for reading the book were to learn the method and  practice it. I had no interest at all in the moral theology. In fact,  the first several months we used NFP, we also used condoms during the  fertile time. It wasn't so much that we didn't want to abstain, but we  honestly didn't trust the method. As soon as we saw three charts where  my body did what the book said it would, we threw away the condoms and  used "pure" NFP. However, I can say that because the Pill had dampened  my libido (and now studies report that effect continues after a woman  stops taking it), I believe we simply did not have the "sex on demand"  attitude that our peers often so. We abstained frequently, mostly because I wasn't interested! Bunching up those days verses spreading
the abstinence out didn't matter much to us.

[I should say that I had a rather dramatic conversion and that  learning about NFP had a major role in it. One night while reading  about how my body worked, I had a blinding moment of infused grace and  I emerged from that experience knowing with certainty not only that  God existed, but that he had created me. One moment, no argument could  have convinced me that God existed and the next, no argument could  have convinced me he doesn't.]

I'm kind of a print junkie. If there is a book laying around, I will  read it, even if it's the Routine Manual on Repairing Toasters.  Because TAONFP was on my bedside, more than once I would pick it up to  browse. Eventually I found myself reading the theology chapters and to  be honest, it just made sense to me. I had spent years being used by  men and degrading myself sexually and I believe there was just  something in my soul that yearned for the noble vision of sexuality  presented in the book. I simply had never heard that sex was supposed  to be anything more than recreational and I was intrigued by the idea.