When did polls became important tour understanding of American religion?

Robert Wuthnow:  ... It wasn’t until the 1950s, during the Cold War period—with the idea that America is a religious country and the Soviet Union is a godless Communist country—that people started gravitating to the idea polls are telling us something interesting. This was also rooted in the notion, increasingly prominent in the 1950s, that science was the big wave of the future. Since Gallup and other pollsters claimed that their polls were scientific, that also attracted attention, at least in the media if not in the general public.

Question:  Then, in 1976, there occurred what you call “the most notable instance to date in which polling played a major role in defining a significant feature of the religious landscape.” Could you tell us about the year of the evangelical?

The year of the evangelical was 1976, when Jimmy Carter achieved election to the White House and the role of polling was to greatly expand the number of Americans who were evangelicals.

How is that possible that a poll could do that? George Gallup, Jr. was now in charge of religious polling at the Gallup Organization. George Jr. was a born-again Episcopalian himself, and had started doing more polls about Evangelicals. When Jimmy Carter came along, journalists were asking themselves, “What does it mean to be a born-again Evangelical?” George Gallup, Jr. had the answer, because he’d asked questions in his polls about whether people considered themselves born again, had ever had a born-again experience, what they believed about the Bible, whether they considered themselves Evangelicals, and so forth.

Gallup said there might be 50 million American who are evangelicals, and journalists ran with that. It was a much higher number than had been assumed before, [which were based on counting members of those denominations within] the National Association of Evangelicals.

In addition to changing the numbers, polling also changed political perception, [by implying] that evangelicals were a voting bloc. That made sense to journalists because Catholics were a voting bloc for John F. Kennedy in 1960—so surely evangelicals must have been a voting bloc for Jimmy Carter. That wasn’t the case at all. Some of the leading, most powerful, influential evangelical leaders were actually for Gerald Ford. There was a lot of diversity among evangelicals themselves that got masked by being lumped together in the polls as if they were all the same thing.