Huh, I'd always assumed that evangelicals like Jerry Falwell got into politics back in the late 1970s because of Roe v. Wade, but in her Falwell obit today, Michelle Goldberg says that's just not true:
The religious right's creation myth holds that Roe v Wade so outraged the faithful that they could no longer sit passively on their pews. As the Columbia University historian Randall Balmer has shown, this is nonsense. The Southern Baptist Convention, Falwell's denomination, was officially pro-choice throughout the 1970s; anti-abortion activism was seen as the province of Catholics, a group then widely despised by fundamentalist Protestants.
No, what really galvanized the religious right were Supreme Court rulings stripping whites-only Christian academies, like the one Falwell founded in 1966, of their tax-exempt status. Fervent opposition to abortion, which eventually cemented the alliance between conservative Protestant and Catholics, came later.
Update: Kevin Drum sees things a little differently.