It's religion and politics season again, as can be seen in a number of recent posts here. For some historical perspective, Frank Lambert of Purdue University is always a good guide. Lambert's most recent work Religion in American Politics is reviewed by Aziz Huq here. One interesting passage in the review (reminiscent of the argument presented in Akhil Ahmar's study of the Bill of Rights):
Lambert does not consider why religious conflict did not break out to the degree that it did in other parts of the world. Surely no explanation can be entirely satisfactory. But several are worth exploring. Chief among them, in my view, is the role of the First Amendment to the United States Constitution. It is not, however, the Amendment’s guarantee of religious freedom that has done the work. Rather, it is the original, and too often forgotten, consequence of the Establishment Clause, which insulated the federal government from formal capture by any sect. State establishments, by contrast, persisted until 1833. It was only the Reconstruction Amendments that extended the protections of the Bill of Rights to the states and thereby rendered state establishments beyond constitutional bounds. But by placing the national policy beyond religious demarcation at the very inception of the American project, the Framers wisely extinguished a source of potentially catastrophic conflict. The common emphasis on religious freedom or the propriety of religious arguments in the public sphere misses this key point.