The accelerating fragmentation of the strife-torn Episcopal Church USA, in which several parishes and even a few dioceses are opting out of the church, isn't simply about gay bishops, the blessing of same-sex unions or the election of a woman as presiding bishop. It also is about the meltdown of liberal Christianity. Embraced by the leadership of all the mainline Protestant denominations, as well as large segments of American Catholicism, liberal Christianity has been hailed by its boosters for 40 years as the future of the Christian church. Instead, as all but a few die-hards now admit, all the mainline...