Are those Christians unwilling to defend their right to live, to fight, to survive? Usually but not always its the atheist or agnostics or the types like the Jehovahs Witnesses that won’t fight.
Most warriors that I know of through history are very christian.
As you know, most of the “developing” (underdeveloped) world are some form of military dictatorship, or with very corrupt democratic forms (that don’t work very well...). So while yes, these Christians are willing to fight for their lives...under heavy dictatorships, or corrupt regimes, that is often impossible.
Take Nigeria for example, where something like 72 million are Christian (and of the serious evangelical variety), another 72 million there are Muslim and are attempting to institute Sharia law in places...and yes it is resisted, while hundreds (and even thousands) get murdered by the Muslims. A very dicey situation there for Christians, who don’t control the government and don’t have the military means at their hands for their own defense.
Besides that, as shown in our own history—civil wars are something to be avoided if AT ALL possible, as they tend to kill many, many people—especially innocents.