“Doug Montzka, a contractor from St. Paul, describes himself as a devout Christian, a very conservative Republican and, only recently, a supporter of same-sex marriage.
He cannot pinpoint the moment he changed sides — his views have evolved, he says — but he does know that five years ago, he never would have voted for it.
While he trusts most everything in the Bible and knows that Leviticus condemns homosexuality as an abomination, “there’s no other reason I can think it’s wrong except the Bible,” he said.
“I’ve coached youth sports for years and had a few kids with gay parents,” said Mr. Montzka, 53. “As far as I’m concerned, if it works for them, it’s O.K. with me.”
While he worries that society could be changing too rapidly, he also sees changes for the better. “My brother married a black girl, and that worked out great for them,” said Mr. Montzka, who is white. “You’d never see that 50 years ago.”
He believes that his business dealings with gay couples would be simpler if they were married. “I’ve had cases,” he said, “where it’s one telling me the other one is supposed to be paying the bill.”
The ultimate decision maker was his conservative distrust of government interference in people’s private lives. “If I’m going to make a mistake,” he said, “it’s on the side of less government.”
On many fronts, Mr. Montzka’s change of heart reflects what opinion and exit polls have been showing in recent years: a sharp increase in support for same-sex marriage in a short time among every age group, including the biggest voting group, the baby boomers.
In a Pew Research poll taken at the end of October, 49 percent favored same-sex marriage, versus 37 percent in 2009.
In that period, according to Pew, support among baby boomers (ages 48 to 66) has grown to 41 percent from 32 percent; among seniors (over age 67) to 33 percent from 23 percent; among Generation X (ages 32 to 47) to 51 percent from 41 percent; and among millennials (ages 18 to 31) to 64 percent from 51 percent.
The shift in attitude has been reflected recently in the courts and at the ballot box. On Dec. 7, the Supreme Court agreed to review two cases related to same-sex marriage. In Washington State, same-sex marriage became legal on Dec. 6. It will become legal in Maine on Dec. 29 and in Maryland on Jan. 1.
One reason behind the surge is evident from both opinion polls and interviews for this article: there is a marked increase in the number of people of all ages who know gay men and lesbians.
Put another way, when it comes to public support of same-sex marriage, familiarity breeds contentment.
In May, 69 percent of adults in a New York Times/CBS News poll said they had a gay colleague, close friend or relative, compared with 44 percent in 2003. By age group, 77 percent of baby boomers in 2012 knew someone who was gay, versus 42 percent in 2003. For 18- to 49-year-olds, it was 70 percent, up from 49 percent; and for seniors, 54 percent, up from 27 percent.
In 1988, 15 percent of 18- to 34-year-olds — the age of baby boomers at the time — supported same-sex marriage, according to the General Social Survey, which is financed by the National Science Foundation. Now, among 18- to 34-year-olds — the millennials — 63 percent do.
Jimmy Weaver, 58, of Oakland, Tenn., an outlying suburb of Memphis, describes himself as “somewhat conservative.” Mr. Weaver enters a lot of people’s houses in connection with his heating and air-conditioning business, including the homes of gay couples. “To be honest with you, most of them are very nice,” he said. “It has no effect on the way I think about them or they think about me.”
Mr. Weaver said that society needed to accept lifestyle changes, regardless of what the Bible teaches.
“To me, their day of judgment is up to them,” he said, “the way they choose to live life.”
Another supporter, Ron Le Blanc, 58, a conservative Republican and retired deputy sheriff in West Linn, Ore., knows many gay people, including his barber, a waiter at his favorite coffee shop and a relative. “I have a cousin who’s very bi, went every which way,” he said. “She took me into a fully gay bar. It was a good time. These people have a sense of humor.”
In the case of David Hanson, 62, a retired businessman living in Naples, Fla., who describes himself as a conservative Republican, the about-face came about a year and a half ago as he started to follow the issue in the news. Suddenly, same-sex marriage was no longer a far-fetched abstraction (“It annoyed me how vocal the gay community was,” he said). It had become an idea that thoughtful people were debating seriously.
“I don’t have any gay friends,” he said. “I can’t put my finger on any specific thing. I just think it’s the right thing to do.”
Growing up in the Soviet Union, Svetlana Goykhman, 51, of Brooklyn, an insurance agent who considers herself very conservative, said she did not know anyone who was gay. “I never saw them, never met any,” she said. “It was a scary thing to say. Gay people could be killed.”
When she immigrated here, it was in department stores, like Saks, where she first met gay people. “I had makeup people, I was buying from, I spoke to them,” Ms. Goykhman said. “For clothes and styles, too — they’re the same people, if anything they’re nicer.”
“In my old country, they told you what you need to do, what you have to do, what you cannot do,” she said. “This is why I left.”
Asked if she is a supporter of same-sex marriage, Ms. Goykhman said: “Yes, of course. We live in a free country.””