PRINCETON, NJ -- Americans who oppose the legalization of same-sex marriage, 46% of the adult population, are most likely to explain their position on the basis of religious beliefs and/or interpretation of biblical passages dealing with same-sex relations.

Other reasons given by those who oppose same-sex marriage include the conviction that marriage should be only between a man and a woman and the view that same-sex marriage is morally wrong or against traditional beliefs. Smaller percentages say that civil unions should be sufficient, that same-sex marriage is unnatural or against the laws of nature, or that same-sex marriage would undermine the traditional family structure.

These data are from a Nov. 26-29 USA Today/Gallup poll that explored a number of issues relating to the status of gays and lesbians in American society. Gallup.com will report additional findings later this week.

Supporters Cite Equal Rights and Personal Choice

Those who favor same-sex marriage are most likely to explain their position by saying either that it is a matter of equal rights, or that such things should be left to the personal choice of those involved. Other supporters say that it is not other people's business to decide who should get married, or that they personally know people who are gay or lesbian.

Fifty-Three Percent Favor Same-Sex Marriage; Ties Record High

Overall, 53% of Americans believe same-sex marriages should be recognized by law as valid, with the same rights as traditional marriages -- tying with May 2011 as the highest level of support Gallup has found since it began tracking the issue in 1996. Forty-six percent say such marriages should not be legal.

More than two-thirds of Americans were opposed to same-sex marriage in 1996 when Gallup first asked about the issue, and the majority were opposed as recently as 2010. But half or more of Americans have supported same-sex marriage in three out of the four Gallup surveys conducted since May 2011.

Young Americans, Democrats, and Those Who Don't Attend Church Most in Favor

Seven in 10 weekly church attenders are opposed to same-sex marriage, while seven in 10 of those who seldom or never attend church are in favor. This dramatic difference in position on same-sex marriage based on religiosity underscores the power of the relationship between religion and attitudes toward moral and values issues in America today.

The biggest differences by age in support for same-sex marriage occur at the extremes, with 34 percentage points separating 18- to 29-year-olds and those 65 and older. Support among Americans aged 30 to 64 is basically split, mirroring the national average.

Republicans are the most opposed to same-sex marriage, while Democrats are the most in favor. Independents tilt toward support -- close to the national average. This finding relates to the fact that party identification in the U.S. today is correlated with religiousness, with Republicans substantially more likely to be religious than independents or Democrats.

Implications

This survey confirms a significant change in American attitudes toward same-sex marriage -- with support rising to 53% today from 42% eight years ago and 27% in 1996. The issue is still divisive, however, particularly along age and political lines. Americans under the age of 30 and Democrats highly favor same-sex marriage, while those aged 65 and older and Republicans significantly oppose it.

These results also underscore the importance of religion as a correlate of these attitudes. A simple indicator of religiosity -- religious service attendance -- is a powerful predictor of views on same-sex marriage, with seven in 10 of those who attend weekly saying they are opposed, and seven in 10 of those who seldom or never attend saying they are in favor. Significantly, when asked to explain their position, almost half of those opposed to same-sex marriage focus on religion, including the statement that such a position follows the respondent's religious beliefs, or that it is based on their interpretation of the Bible.