In this approach presidential candidates make their religious faith demonstrably public and wield it as a campaign centerpiece. Out is a traditional wall of separation; in is a “bridge between church and state” that George W. Bush—who used the God strategy to perfection in 2000 and 2004—offered early in his presidency.

This is not how it’s always been.

God and religion have always been part of U.S. politics, but our analysis of more than 15,000 public communications by political leaders from Franklin Roosevelt’s election in 1932—the beginning of the modern presidency—through six years of George W. Bush’s administration revealed a striking increase in public religiosity beginning in 1980.

That year, in response to Jimmy Carter’s personal faith story, Ronald Reagan ran a campaign shot through with religious themes and calculated visits with newly mobilized evangelicals. This approach was so successful that subsequent presidents have followed suit. The result is that presidential candidates today use religion as a political weapon: to organize and explain one’s values, to justify policy plans, and—most importantly—to divide the electorate into allies and enemies.

The victors in Iowa on Thursday have used the God strategy to a degree rarely seen in modern history. Obama’s public embrace of faith began in 2006 with a keynote address at Sojourners magazine’s Call to Renewal conference. Syndicated columnist E.J. Dionne suggested the speech “may be the most important pronouncement by a Democrat on faith and politics since John F. Kennedy’s Houston speech in 1960 declaring his independence from the Vatican.” Later in 2006 Obama spoke at an AIDS summit hosted by Rick Warren—a conservative who is one of the most prominent evangelicals in the world.

Since then, Obama’s religious politics have only grown. He often begins speeches—including his address in February 2007 in which he announced his intention to seek the presidency—by giving “all praise and honor to God,” and regularly cites the biblical story of Joshua. In Iowa, Obama had a faith steering committee and his campaign held forums across the state titled “What’s faith got to do with it?”

Still, he lagged behind Huckabee in his religious politics. Early on, the little-known ordained Southern Baptist minister compared himself to Biblical underdogs David and other Old Testament prophets. He wowed Christian conservatives at the Family Research Council’s Values Voters Summit in October, saying “I think it’s important that the language of Zion is a mother tongue, and not a recently acquired second language.” Huckabee began to surge in Iowa polls not long after, a rise he attributed to divine intervention.

Huckabee sealed his ascendancy by airing perhaps the most religious ads in U.S. presidential history. A signature spot featured Huckabee saying “Faith doesn’t just influence me; it really defines me,” as the words “Christian leader” flashed across the screen. In another ad, Huckabee asked viewers to remember the real meaning of the holiday season: “the celebration of the birth of Christ.” When this message stirred up controversy, Huckabee adroitly painted himself as the target of secularists.

Obama and Huckabee: Two presidential candidates, two political parties, one approach—and the same result. The question now is whether this strategy has legs beyond Iowa.

As the candidates turn their attention to New Hampshire, they’ll find voters who are likely to be a bit more cautious about too intimate a relationship between religion and politics. But soon thereafter comes South Carolina, where faith runs wide and deep. Indeed, Obama’s campaign had a “40 days of Faith and Family” focus there in autumn.

One thing is for sure: we’re light years and a religious political revolution from John F. Kennedy’s candidacy in 1960, when he famously declared that “I believe in an America where the separation of church and state is absolute” and “I believe in a president whose views on religion are his own private affair.” That was a winning message then. Today it would be a voice in the wilderness—on both sides of the partisan aisle.