"The ban on contraception is completely irrelevant to Catholics," said Jon O'Brien, president of the group Catholics for Choice. "We know the position the hierarchy has on contraception is fundamentally flawed, and that's why it's ignored en masse."

The Rev. Ken Vialpando, pastor of St. Joseph Catholic Church in Ogden, Utah, places much of the blame for Catholics' disobedience on priests who are reticent to talk about church teachings on marriage and sex, or who bought into the 1960s notion that one's conscience was a sufficient guide.

"What if our consciences are not fully informed?" Vialpando asked. "How can we fault the people if they haven't heard about it and recognize the purpose or meaning of marriage?"

Smith, whose recorded 1994 talk "Contraception, Why Not?" has sold more than 1 million copies, says young adult evangelicals and Catholics, including men studying for the priesthood, seem more open to the possibility that contraception is a sin.

The pendulum may yet swing, she said.

"They are going to have a huge impact," says Smith, who holds an ethics chair at Sacred Heart Major Seminary in Detroit. "They already are."

The Rev. Greg Johnson of Sandy, Utah, who is on the board of the National Association of Evangelicals, says most evangelicals remain firmly in the contraceptive camp, even if some stress that it should not be used frivolously or to avoid children altogether.

A recent Gallup poll of the association, and another of its board, found 90 percent support for contraception.

Such statistics are disheartening for evangelicals such as Hodge and James Tour, a renowned chemist specializing in nanotechnology at Rice University in Houston, who believe contraception is not biblical.

Rather than heeding Christian theology to be "agents of life in the world," Christians have largely adopted culture's philosophic naturalism, which considers sex an itch to be scratched, Hodge said.

"They have the same view of conception that atheists have."

Evangelicals' dearth of understanding about sexuality and marriage explains why they have trouble arguing against gay marriage, he contends. Contracepted sex, in his view, is no different from gay sex: It's not life-giving either way.

Tour, a Jew who converted to evangelical Christianity as a teenager, like Catholics endorses "natural family planning" -- avoiding intercourse during the woman's monthly fertile cycle -- but wonders if Christians ought to forgo even that measure of family planning.

He says young lustful men who have had unfettered access to their wives actually welcome a message of self-restraint.

"The women are looking for relief. The men are looking for relief," Tour says. "They're like, 'I want that. I want to live in peace. I want to live in fulfillment.'"

Throwing out contraception "is more trusting in God. It ultimately lets him decide what is the right number (of children)," Tour said. "Protestants in 30 or 50 years are going to say, `My God. What were we thinking in those generations?'"

Copyright 2010 Religion News Service. Used by permission. All rights reserved.