Swartz says Carter represented a growing movement in the 1960s and '70s of Christians motivated by social justice issues like combating poverty and war.
The book centers on the stories of several of them, like Mark Hatfield, an anti-Vietnam War activist who was a moderate Republican from Oregon, and the Rev. Jim Wallis, a 1970s social justice activist who is the founder and editor of Sojourners magazine.
Carter's election was a moment that the evangelical left could have seized, but didn't, Swartz says, in large part because his presidency was perceived to be a failure. He was swept out of office in 1980 by Ronald Reagan in an electoral landslide, with massive support from evangelical Christians. And conservatism became synonymous with Christianity, Swartz says largely because of one issue.