Hamburger's "Separation of Church and State"

The latest University Bookman contains a review of Philip Hamburger's Separation of Church and State", which delves into this "stubborn ideology". Hamburger recounts the evolution of the "wall" argument, hitting all of the appropriate touchstones. But then there's this:

In fact, it was not until the 1840s that the idea of separation of church and state really began to gain wide acceptance, as native born Protestants, alarmed by increasing numbers of Catholic immigrants, and viewing the Catholic Church as an obscurantist, authoritarian institution that, ruled by a foreign prince, exercised a kind of mind control over its members, embraced separation of church and state as a way of limiting the grave threat they believed Catholicism posed to American freedom....Nativist Protestants used the idea of separation of church and state to restrict the influence of Catholic clergy in politics and to eliminate public support for Catholic education.

Particularly notable in this regard was the school question, where nativist legislatures, seeking to make the public or common school an agent of both Americanization and Protestant evangelization—the two were closely linked in their minds—promoted common schools in which a non-denominational Protestantism was taught, the (Protestant) King James version of the bible was regularly read, and textbooks filled with anti-Catholic propaganda were used, even as they refused public support for “sectarian” Catholic schools because such support would allegedly violate the separation of church and state. Nativists could hold these contradictory positions because...they did not think of themselves as part of a structured, hierarchical church; accordingly, as they saw matters, supporting a non-denominationally Protestant public school system while denying funds to Catholic schools on separationist grounds made sense because what they sought was the separation of church from state, not of (the Protestant) religion from government.

...recognizing that the Constitution did not actually mandate separation, nativists began in the 1870s to propose constitutional amendments intended to make separation the law of the land and to preclude any possibility of public funding for “sectarian,” that is, Catholic schools, while leaving the non-denominational Protestant public school system fully intact... Yet, ironically, while nativists recognized that the First Amendment did not in fact separate church and state, they do not seem to have recognized that the logic of separation, strictly applied, would require the secularization of the public schools...

Ah yes, unintended consequences...