It's moral to abstain from sex for other, somewhat trivial reasons, Smith noted - a spouse with a headache, someone would like to finish a book, someone wants to catch a sports game, the walls are too thin, etc.
"So I have a simple question for you. Why would it be wrong not to have sex because it's not a good idea to have a child at that time?" she said.
"I'm certainly going to affirm that children are the primary purpose of marriage and commend the Providentialists for their devotion to that good," Smith said, "but I'm going to challenge the claim that [just reasons to abstain] only mean the woman's near death or the family's financial ruin."
The culture at large, on the other hand, misunderstands sexuality as something "nasty and naughty," and sees children as an optional means of personal fulfillment or a hobby, Smith said, rather than as a supreme gift from God resulting from the gift of sexuality within the context of marriage.
"They don't see [sex] as a huge gift from God that God has given to spouses as a means to let them help him create new human souls," she said.
"[Children] are a supreme gift of marriage, they give people meaning, purpose, joy, unbelievable laughter...and bills to worry about and all kinds of things," Smith said. If Christians believe they are raising up souls for God, "why wouldn't they want to have a lot of children?"
But while the Church recognizes children as a gift and asks couples to be generous in their openness to life, it also allows for couples to abstain from sex during the fertile phase for "serious" and "just" reasons, including "physical, economic, psychological and social conditions," Humanae Vitae states.
Furthermore, it notes that "responsible parenthood is exercised by those who prudently and generously decide to have more children, and by those who, for serious reasons and with due respect to moral precepts, decide not to have additional children for either a certain or an indefinite period of time."
What counts as serious or just enough reasons? "It's between you and God," Smith said. "One thing you have to do [to use NFP] is to learn how to pray, and to learn how to say, 'What do you think, God?'"
It is possible to use NFP selfishly, Smith noted, but she added that the cure for that selfishness can also be found within the use of NFP, since it facilitates conversations between the couple about their family and relationship. Furthermore, she said, most people want to have sex, meaning that abstaining from sex requires a self-mastery that is not characteristic of selfish people.
"If you believe you've got good reasons [to abstain], go ahead and use NFP, but keep praying, and tell God: 'If we're being selfish with NFP, let us know,'" she said.
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When asked what the biggest hurdles are for Catholics and non-Catholics alike when it comes to accepting Church teaching on this issue, Smith said it is a misunderstanding of both contraception and NFP within both groups.
"They don't have any idea the damage that the hormonal contraceptives do to a woman's body, so they don't even know they should be looking for something else," Smith told CNA. Furthermore, "they don't understand the many benefits that abstinence brings to a relationship, and it needs to be acknowledged that it's difficult. It's as difficult as dieting, and budgeting and exercising regularly, but everybody knows that those bring great benefits to those who do those things. And if you have a necessity to do them, they're that much easier, because you have a necessity," she said.
It's important that the Church keep teaching the truths of Humanae Vitae even 50 years after its original publication, Smith said, because most people still don't know the truth, and it has also become "more and more overwhelmingly clear that it was right, that contraception would be devastating to relationships and to cultures."
Smith added that she was encouraged by the symposium at Benedictine. "It was astonishing, and these were young people for the most part in some way defending Humanae Vitae," she said. "People who oppose Humanae Vitae seem to think its a dead letter, but we need to show that young people are confirming its truth rather than rejecting it."