The poll of 2,002 adults, conducted Sept. 2-9, has a margin of error of plus or minus 2.5 percentage points. "Since we've seen this upward trend for so long, we're cautious because it's too early to say what this means for long-term trends," said Jessica Martinez, a researcher in Pew's Religion and Public Life Project. The Pew survey also found the percentage of people who consider gay relationships sinful had increased from 45 percent a year go to 50 percent last month, although other surveys have found that people with religious objections don't always oppose legal recognition for gay relationships. Robert Jones, chief executive of Public Religion Research Institute, a nonprofit group that conducts surveys on religion and public life, noted that support for gay marriage has been driven by younger people, who tend to be far more accepting of same-sex relationships than their parents.