Today, the phrase “evangelical left” reads like an oxymoron. White evangelicals, everyone knows, are by and large conservative Republicans.

But evangelicals were not always so predictable. During the 1970s, their ranks included numerous Democratic politicians such as President Jimmy Carter and Sen. Harold Hughes (D-Iowa). Perhaps even more surprising, the movement’s Republican representatives were often moderates or liberals. Examples included Sen. Mark Hatfield (R-Ore.), a devout Baptist who once asked an audience that included President Richard Nixon to fall to its knees in repentance for the “sin” of the Vietnam War; Rep. John B. Anderson (R-Ill.), a future presidential candidate and an advocate of fair housing laws who helped lead the drive for the appointment of a Watergate special prosecutor; and Rep. John Buchanan Jr. (R-Ala.), an ordained Southern Baptist clergyman who supported the Equal Rights Amendment (ERA) and Title IX, which prohibits sex discrimination in educational programming.

What became of this centrist strand of American evangelicalism? One common view holds that as the Democratic Party grew increasingly hostile to “traditional” values, evangelical voters had little choice but to abandon their moderate coreligionists in favor of staunchly conservative politicians who could be counted on to defend their interests in Washington. They learned to elect “street fighters” instead of “nice guys,” as Jerry Falwell Jr., the former president of Liberty University who resigned this week in the wake of scandals involving his personal conduct, put it in 2018.

But this account badly misreads the history of the evangelical movement. In reality, it was not a grass-roots reaction against the growing secularism of the political left that drove moderate and liberal evangelicals out of politics. It was, rather, a brief and coordinated campaign of primary challenges from the right.

The story begins in the early 1970s, when a small band of political operatives began plotting a hostile takeover of the Republican Party. Dubbed the “New Right” by the news media, Paul Weyrich, Richard Viguerie and their allies believed that a monolithically conservative GOP would be well positioned to win the votes of working-class Whites who were dissatisfied with the Democratic Party’s liberal stances on civil rights and other social issues. But for this plan to work, it would first be necessary to purge the Republican Party of its sizable moderate wing.

That many moderate Republicans were outspoken evangelicals posed a particularly thorny problem for the New Right. Indeed, the very existence of politically moderate evangelicals undercut claims that “liberals” were by definition contemptuous of Christianity (a favorite theme of Viguerie’s direct-mail materials). Moreover, lawmakers such as Hatfield and Anderson, who relied on biblical principles to advocate for gender and racial equality, complicated the New Right’s message that civil rights laws were a threat to the traditional family. Hence, Weyrich and Viguerie began planning to oust moderate evangelicals from office. And wherever possible, they relied on conservative evangelicals to spread the word that centrist lawmakers were not to be trusted.