But whose law should prevail? discusses “church, state, and the courts in America”:
The first sign of secularism in American politics came in the late 19th century, largely to camouflage sectarian anti-Catholicism. Nobody objected to public schools teaching the Bible — indeed politicians would have been horrified by any school that did not — as long as it was the Protestant version. When Irish immigrants wanted to use their Catholic version, the Republicans came up with a series of crafty provisions to ban public money from helping teach popish nonsense.