In the Washington Post, Prof. Bradford Wilcox points out:

"The marital misbehavior of Schwarzenegger, a Roman Catholic, not to mention evangelical Protestants such as John Ensign and Mark Sanford, however, should not be mistaken for the norm among married men in America today, and especially for married men who are regular churchgoers. . . .

According to research by the National Marriage Project at the University of Virginia, Americans have become less tolerant of marital infidelity over the last forty years, and somewhat less likely to stray over the last 20 years. For instance, in the 1970s, 63 percent of men and 73 percent of women said marital infidelity is “always wrong.” In the 2000s, 78 percent of men and 84 percent of women said that marital infidelity is “always wrong.”

Likewise, in the 1990s, 17 percent of married men and 11 percent of married women reported that they had been unfaithful to their spouses. In the 2000s, infidelity reports fell to 16 percent and 10 percent, respectively, among men and women.

Infidelity is even less common among men and women who attend religious services regularly. Married men and women who attend church weekly are about half as likely to report sexual infidelity, compared to their peers who never attend church, according to research by sociologist Amy Burdette at Florida State University and her colleagues."