By Dan Gilgoff, CNN.com Religion Editor

(CNN) - Both Todd Akin’s claim that women’s bodies can prevent conception in cases of “legitimate rape” and the GOP’s newly-adopted platform language calling for a constitutional ban on abortion have provoked controversy for largely the same reason: They showcase the belief that all abortions should be illegal, without exception.

But even as Democrats and abortion rights groups use the controversies to reinforce allegations of a Republican-led “war on women,” don’t expect the anti-abortion movement to back away from calls for all abortions to be illegal - even for women impregnated by rape or incest.

“Philosophically, the consensus is very clearly that life is life and that it should be not be taken and that abortion is not a compassionate response to something terrible, even like rape,” said Marvin Olasky, the editor in chief of World magazine, an influential evangelical publication.

“It’s adding one terrible thing onto another terrible thing.”

At the same time, the anti-abortion movement has grown to accept that many Republican politicians are unlikely to echo their “no exceptions” line on abortion. That includes Mitt Romney, whose campaign recently said abortion should be allowed in cases of rape.

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“I don’t think that the Republican Party has ever nominated someone for president who didn’t advocate for an exception for rape and incest and the life of the mother,” said Ralph Reed, who leads the Faith and Freedom Coalition. “So the party has always had a diversity of views on that point.”

Still, Reed said that diversity is mostly born of political reality, as opposed to reflecting serious debate among anti-abortion activists over whether abortion should be legal in certain circumstances. The fact is that Republican politicians who don’t advocate exceptions for abortion bans are less likely to win election.

To the extent that rape and incest exceptions have been advocated, said Reed, "it’s been mostly for political viability and expediency."

In the decades after the Supreme Court’s 1973 Roe v. Wade decision ensured legal protection for abortion procedures nationwide, the anti-abortion movement was initially uncompromising in advocating across-the-board abortion bans at the state and national level.

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But as anti-abortion groups like Operation Rescue failed to meaningfully influence the public policy debate around abortion, the movement changed strategies in the 1990s, looking to chip away at abortion rights rather than expect an across-the-board ban, which couldn’t happen with Roe on the books, anyway.

“Operation Rescue left the impression that they wanted to impose the will of a minority of people on the majority, and a lot of pro-life leaders said that was not working,” said Olasky, who has chronicled the anti-abortion movement and was an informal adviser to President George W. Bush.

“Those leaders said you have to bring others along – that’s American democracy,” Olasky said. “There was a pivot to an incremental approach.”

That approach wound up yielding new anti-abortion legislation, including the Infant Born Alive Protection Act of 2002 and Partial Birth Abortion Ban Act of 2003.

But tensions between pragmatism and idealism among abortion rights opponents continues. It’s reflected in the rift between the Romney campaign and the Republican Party platform around abortion. Platform language adopted Tuesday calls for a constitutional abortion ban without making explicit exceptions for rape or incest.

But Reed, who formerly led the Christian Coalition, charges that the controversy around calls for abortion bans without exceptions for rape or incest –- he says anti-abortion activists generally support abortions to save a mother’s life - has been blown out of proportion by Democrats and liberals who want to paint the GOP as extremist.

The reality, Reed contends, is that abortions that happen in response to rape and incest are a “statistically insignificant portion of abortions as a whole, even as they represent a significant national tragedy.”

The focus on GOP calls for no-exception abortion bans, Reed said, is “an attempt by the left to raise a bogeyman and by the media to raise 'gotcha questions' with candidates who are pro-life.”

Still, he acknowledged that many women who are generally opposed to abortion, want there to be some legal exceptions.

A Gallup poll from earlier this year found that 20% of Americans want abortion to be illegal in all circumstances, while 25% of Americans want abortion to be legal in all circumstances.

Half the country, meanwhile, wants to see abortion legal, but only in certain circumstances, the poll found.

Amid the furor over Akin’s comments - for which he apologized this week, even as many Republican leaders have called for him to end his campaign - many anti-abortion activists have stuck by their stance against abortion rights in the case of rape.

“The most eloquent defenders of the value of every human life are people like my friends Ryan Bomberger and Rebecca Kiessling, both of whom were conceived in rape,” Charmaine Yoest, president of the anti-abortion group Americans United for Life, wrote in a post for National Review Online this week.

“Today, Ryan and Rebecca are vibrant reminders of the truth that Life has value, no matter its beginnings,” she wrote.

Many anti-abortion activists root their strict opposition to abortion rights in the theology of the Catholic Church, which says it has always condemned abortion.

The church does acknowledge that influential Catholic thinkers over the centuries have had different views on when exactly life begins, with some putting that milestone well after conception.

According to the U.S. Conference of Catholic Bishops, the church adopted its position on life beginning at conception in the 19th century.

Many anti-abortion Catholics and evangelicals cite Psalm 139 in the Bible, which says “it was (the Lord) who formed my inward parts; you knit me together in my mother’s womb.”

Though it doesn't mention abortion, antiabortion activists also point to the story of Moses’ birth from the second chapter of the book of Exodus, in which the heroic figure is spared from infanticide.

The text says the Hebrews, who were enslaved to Egyptians, were growing in number. Pharaoh ordered all Hebrew boys born to be killed and thrown into the Nile. Moses’ mother defies the order and when she can longer hide baby Moses, she puts him in a reed basket and floats him down the Nile.

Pharaoh’s daughter discovers the baby in the basket while she is bathing, rescues him, and winds up raising him.

–CNN's Eric Marrapodi contributed to this report.