Every nation needs to defend itself. Yet many nations (including our own at its founding) have been wary of standing armies. The prophet Samuel, in warning Israel against a king, touched on this fear (cf. 1 Sam. 8:11-12). The same suspicion inspired the Roman law that forbade Caesar crossing the Rubicon. The danger of a standing army is simple: It can be used against its own people. Generals can use it against the government and the government can use it against the citizens. Thus, a tension: A nation at once both needs and fears an army.
The Church, like a nation, must defend herself and her faith. She must fight for the truth and for the salvation of souls. This demands doing battle, for which reason we call ourselves the Church Militant. Like a nation, however, the Church also encounters a danger: that the fighting spirit of the Church Militant turn against her. The danger is not of fighting-but of only fighting, and fighting in the wrong way.