It was on natural family planning -- how to avoid, or plan for, a pregnancy without using artificial birth control.
"We never practiced contraception," Cremin said. "We didn't need to because we knew this was adequate. It was difficult at times, it's difficult to practice it at times, but we made the sacrifices and that was it. And spiritually there is a gain to be had from practicing natural family planning."
Cremin and his wife now have five children and teach natural family planning to other couples in the west of Ireland.
The technique involves monitoring changes in a woman's body to pinpoint when she is most -- and least -- likely to conceive.
It's a method consistent with Catholic Church teachings. The church says every act of sexual intercourse should be "open to life" and that it should take place within marriage only.
In other words, nothing should prevent the possibility of a child being conceived. Sex is about love and procreation. Using contraception separates the two. And that, says the church, goes against the design of God.
"The church's position is that by taking the fertility out of the sexuality, contraception eliminates the basis of the [marital] relationship," said Donald Asci, an associate professor at Austria's International Theological Institute. "And without the basis for the relationship it devolves into something else, perhaps a mutual use or a sort of utilitarian approach, but not the kind of love God designed for the man and the woman to have."
In modern times, this position was laid out by Pope Paul VI at the end of the 1960s.
At the time, the contraceptive pill had been introduced, and many other Christian churches already accepted contraception. The question was, would the Catholic Church follow suit?
"But the teaching of the pope was clear -- we can't remake doctrines," Asci said. "They are not of our own making, so they can't be remade. These are things we are handing down, having received them from the teaching of [Jesus Christ's] apostles and divine revelations. They are not policies to be made by the pope."
Other religions take a softer line on contraception. Protestant Christian churches and Judaism generally allow it. Islam permits it for various reasons.
Many Catholics -- particularly in rich countries -- are dismayed at their church's harder line.
"We're told that people shouldn't practice artificial means of birth control if they want to be good loyal Catholics, but if you go to church on a Sunday you clearly see they are practicing birth control," said Dr. Lavinia Byrne, a former nun who has called for the church to allow contraception for married couples. "You used to see families with six, eight children, but now there are families with two, three children appearing on a Sunday. This is very bad for the church, because it means at the heart of Catholic life there's a lie, where people are saying one thing and doing another. The door of their bedrooms is being closed against papal teaching and somehow the church has to grapple with this problem."
But there's perhaps a greater challenge -- AIDS.
Organizations fighting AIDS promote condoms as one of the best ways of preventing the HIV virus from spreading.
But the church forbids their use and says anti-AIDS campaigns should emphasize marital fidelity and abstinence instead.
"These programs [emphasize] that we are human beings with a great deal of dignity, we are not animals, we don't just carry on with sexual compulsions," said Anthony McCarthy, who works with the Linacre center, a bio-ethics center linked to the Catholic Church. "[Handing] out condoms and [hoping] that that solves the problem -- the church says that's not a way of treating human beings seriously, and it doesn't actually help prevent the spread of the disease."
It's that position that has angered many AIDS activists. They accuse the church of undermining prevention efforts.
And, increasingly, some criticism is also coming from within the church.
Belgian Cardinal Godfried Danneels said last year that using condoms would be justified when one partner is HIV-positive.
Other influential church figures have made similar comments.
Maureen Junker-Kenny, a lecturer on Christian ethics at Trinity College Dublin, said the issue is complex. She said that widespread availability of condoms is not the answer to AIDS in the developed world, as it could promote promiscuity. But she said it's different for poor countries.
"I think the case of being able to protect oneself from becoming ill with AIDS through one's marital partner -- that case is totally compelling," said Junker-Kenny. "One is making victims if one is saying it's only through marital fidelity [that people can protect themselves]. Because what can a woman do to control her partner's fidelity? She can't. If he makes his children motherless and contributes to his wife dying, then one has to see the evil committed through that prohibition of condoms."
Pope John Paul II, who died on 2 April, strongly upheld the church's traditional values and was unbending in his opposition to birth control.
Wherever they stand, Catholics and non-Catholics alike will be looking with interest to see how the church deals with the issue under his successor.
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