Word Origin & History
1838, said by Weekley to be first recorded in Gladstone's "Church and State," "in reference to a scheme directed against the Church of England," from establishment in the sense of "the ecclesiastical system established by law; the Church of England" (1731). Hence, establishmentarianism "the principle
of a state church," and disestablish (1590s) "to deprive (a church) of especial state patronage and support" (first used specifically of Christian churches in 1806). Rarely used at all now except in examples of the longest words, amongst which it has been counted since at least 1923.