We do not find, of the Christian Religion either, that it always disdained the sword, when once it had got one.

Thomas Carlyle (1795-1881) Scottish essayist and historian

Lecture (1840-05-08), “The Hero as Prophet,” Home House, Portman Square, London
    (Source)

On accusations of Islam being spread "by the sword."

The lecture notes were collected by Carlyle into On Heroes, Hero-Worship, & the Heroic in History, Lecture 2 (1841).