Rich Lusk observes in his insightful On Being the Church in America:
Secular space had to be imagined ex nihlo and then constructed from scratch in order create a sphere of human life which would be governed by “pure reason,” free from the dogmatic prejudices of “religion.” Or to put it another way, a “private religion” (under the guise of “Christianity’) had to be invented in which the religious life was fully severed from public and political life.
Resurrectio et Vita 