From "The Social Contract:"
"But I am mistaken in speaking of a Christian republic; the terms are mutually exclusive. Christianity preaches only servitude and dependence. Its spirit is so favourable to tyranny that it always profits by such a régime. True Christians are made to be slaves, and they know it and do not much mind: this short life counts for too little in their eyes.
"I shall be told that Christian troops are excellent. I deny it. Show me an instance. For my part, I know of no Christian troops. I shall be told of the Crusades. Without disputing the valour of the Crusaders, I answer that, so far from being Christians, they were the priests' soldiery, citizens of the Church. They fought for their spiritual country, which the Church had, somehow or other, made temporal. Well understood, this goes back to paganism: as the Gospel sets up no national religion, a holy war is impossible among Christians."