The Supreme Court hears oral arguments on Tuesday in a case that weighs whether state bans against same-sex marriage violate the constitution’s guarantee of equal protection for gay and lesbian couples. Ahead of the ruling, many religious conservatives are reiterating their opposition to allowing gay and lesbian couples to marry legally. Although public opinion has shifted dramatically, especially among religious Americans, many leaders of the conservative Christian political movement continue to act as if public opinion were frozen in the 1970s. But in fact, more religiously affiliated Americans now support same-sex marriage than oppose it.

Many religious conservatives continue to insist that the same-sex marriage debate pits religious Americans against non-religious Americans. That was largely true even as recently as 2003, when Massachusetts became the first state to legalize gay marriage. That year, there were no major religious groups among whom a majority supported allowing gay and lesbian couples to marry. The highest levels of support among major religious groups came from white mainline Protestants, of whom 36 percent favored same-sex marriage, and Catholics, with 35 percent support. Nearly two-thirds of the religiously unaffiliated, by contrast, supported same-sex marriage.

Over the last decade, though, the debate has shifted from one between religious and non-religious Americans to one that primarily pits older, conservative Christians against moderate, progressive, or younger Christians, Jews, and the religiously unaffiliated.

Today, there are religious groups on both sides of the same-sex marriage debate. Public Religion Research Institute’s American Values Atlas—based on 40,000 interviews—shows some striking realignments over the last decade. A number of major religious groups have joined the unaffiliated in supporting same-sex marriage. In addition to the more than three-quarters of the religiously unaffiliated who support same-sex marriage, 84 percent of Buddhists, 77 percent of Jews, approximately six in ten white mainline Protestants (62 percent), white Catholics (61 percent) and Hispanic Catholics (60 percent), and 56 percent of Eastern Orthodox Christians now support allowing gay and lesbian couples to marry legally.

On the other side of the debate, 68 percent of Jehovah’s Witnesses, 66 percent of Mormons and white evangelical Protestants, and more than half of Hispanic and black Protestants oppose same-sex marriage.

These reconfigured battle lines are also evident in the dueling friend-of-the-court briefs filed by two different groups of religious organizations—one urging the court to overturn bans on same-sex marriage and one arguing to uphold them.

Conceding the loss of some religious groups in their ranks, many conservative religious leaders nonetheless continue to assert that religious Americans overall continue to oppose same-sex marriage. Even among religiously affiliated Americans, however, supporters today actually slightly outnumber opponents. Among all religiously affiliated Americans, 47 percent favor allowing gay and lesbian couples to marry, compared to 45 percent who oppose. (The survey’s huge sample-size makes even this narrow margin statistically significant.)

This new terrain is not only lost on conservative religious leaders; opponents of same-sex marriage, more than other Americans, remain convinced that public opinion is on their side. In early 2014—more than a year after national polls began consistently finding majority support for same-sex marriage—Americans who opposed legalizing same-sex marriage were roughly three times more likely to say that most of the country opposed rather than supported same-sex marriage.

Because support for same-sex marriage is higher among religiously unaffiliated Americans, many wrongly believe that the movement of non-religious Americans are primarily responsible for the new battle lines. But in fact, the bulk of the shift in favor of same-sex marriage over the past decade has taken place among religious Americans. While more than three-quarters of religiously unaffiliated Americans favor same-sex marriage today, that number is up only 12 percentage points since 2003.


Increase in Support for Same-Sex Marriage Among Select Religious Groups

Pew Reseach Center / PRRI / American Values Atlas

Support among all religious Americans, however, has jumped nearly 20 percentage points, from 28 percent in 2003 to 47 percent in 2014. Among some religious groups, such as Catholics (up 25 points, from 35 percent to 60 percent support) and white mainline Protestants (up 26 points, from 36 percent to 62 percent support), the rise in support has been even more dramatic. Even white evangelical Protestants, who remain one of the groups most strongly opposed to same-sex marriage, have more than doubled their support (from 12 percent to 28 percent) over the last decade. And among younger white evangelical Protestants between the ages of 18 and 29, support sits at 45 percent.

The significance of this tipping point—where more religious Americans than not support allowing gay and lesbian couples to marry legally—is difficult to overstate. It changes the fundamental premises of the debate. Claims, for example, that a decision by the Supreme Court in favor of legalizing same-sex marriage would be tantamount to an “open season on people of faith” never fully captured the complexity of religious opinion. Today it is flatly inconsistent with the best available data we have on the considered opinions of religious Americans. Simplistic appeals to a “moral majority” on this issue are likely to undermine, rather than buttress, their position. Any contemporary argument against same-sex marriage that appeals to the beliefs of religious Americans will instead have to make the case for why the objections of one group of religious Americans—an increasingly minority group—should outweigh the opinions of other religious Americans and the nation as a whole.