THE end is near — or so it seems to a segment of Christians aligned with the religious right. The global economic meltdown, numerous natural disasters and the threat of radical Islam have fueled a conviction among some evangelicals that these are the last days. While such beliefs might be dismissed as the rantings of a small but vocal minority, apocalyptic fears helped drive the antigovernment movements of the 1930s and ’40s and could help define the 2012 presidential campaign as well. Christian apocalypticism has a long and varied history. Its most prevalent modern incarnation took shape a century ago,...