Back in 1969, the same year as Woodstock, Gallup Poll researchers asked Americans this moral question: "Do you think it is wrong for a man and a woman to have sexual relations before marriage, or not?" "Yes, wrong," responded 68 percent of those polled, while 21 percent said, "No, not wrong."

By 1973, the traditionalist camp affirming that premarital sex was wrong was down to 47 percent and the minority of those disagreeing rose to 43 percent. In 1991, only 40 percent considered premarital sex immoral, with 54 percent disagreeing.

Anyone paying attention to the moral math could see the trend. By 2001 the number of Americans who took the conservative stance was leveling off at 38 percent, but the percentage of those embracing the liberal, progressive position was up to 60 percent. The numbers were relatively flat in 2011, with 60 percent accepting premarital sex and 36 percent continuing to call it immoral.

"Things have been pretty steady recently among the Americans who are religiously active," noted Ed Stetzer, the president of LifeWay Research, which is linked to the 16 million-member Southern Baptist Convention. "The real action has been on the other side of the spectrum, among the people who are atheists, or agnostics, or who have no affiliation with any particular religious group.

"Then you have the people that I call the 'mushy middle,' who remain connected to some religious faith, sort of, but not active in any real sense of the word. ... That's where we're seeing people changing their minds on sexuality."

The results of a recent LifeWay survey suggest that Americans who have, in recent decades, embraced premarital sex as a moral norm are continuing to edit their beliefs to go with the flow of the Sexual Revolution.

The hot-button issue at the moment, of course, is same-sex marriage. This is a political and cultural puzzle that -- for believers in a various world religions -- is closely connected to a number of ancient doctrines linked to sexual morality.

According to a November 2012 survey by LifeWay, only 37 percent of adults in the United States affirmed traditional teachings that homosexual behavior is sinful. This finding was significant since 44 percent took that stance in another survey -- asking the same question -- only 14 months earlier. The number of respondents saying, "I don't know" also rose 4 percent, to 17 percent.

What happened in between? The researchers were very aware, said Stetzer, that -- halfway between these two surveys -- President Barack Obama announced a long-expected change of heart and openly endorsed same-sex marriage.

While the president's words may have helped move some of the numbers, the change among African-Americans appeared to be minimal, with 36 percent saying homosexual acts were sinful in the first survey and 34 percent in the survey 14 months later. That shift was within the survey's margin of error.

As would be expected, Americans identifying as "born-again, evangelical or fundamentalist" Christians were -- at 73 percent -- most likely to call homosexual behavior a sin. Only 33 percent of Catholics in this survey agreed.

A clear "pew gap" also emerged, as usual, with 87 percent of those who said they attend worship services once a week or more affirming the traditional doctrinal stance. On the other side, only 17 percent of those who said they "never" attend worship services said that homosexual behavior is a sin.

In light of these trends, it's easy to see why the Rev. Louie Giglio, an evangelical leader in campaigns against human trafficking, was accused of anti-gay rhetoric and forced to withdraw from giving the benediction at the second Obama inauguration rite.

In a sermon recorded 15 years earlier, Giglio had said: "If you look at the counsel of the word of God -- Old Testament, New Testament -- you come quickly to the conclusion that homosexuality is not an alternate lifestyle. ... Homosexuality is sin. It is sin in the eyes of God, and it is sin according to the word of God."

Clearly, these words are highly offensive to defenders of the Sexual Revolution. Indeed, times have changed.

Giglio's words, said Stetzer, were "simply mainstream evangelical expressions of what traditional Christians have believed for 2,000 years. ... But what we are learning is that a growing majority of Americans no longer feel comfortable with words like 'sin.'"