This research was carried out in order to ascertain what action the Christians should take when they encounter terrorism.The research was historical and analytical studies carried out through library research as well as the use of structured interview guides, which wereadministered on the clergymen, academia, and others in the society. In the course of research, the researcher discovered that the concept of Just War existed even before the era of St. Augustine among the Asians, the Chinese, and Greco-Roman World and has been used to represent a war that was fought for a just cause, and as the last resort. St. Augustine later adopted it as a Christian standard because of his conviction of the existence of such war theory among the Judeo-Christian concept of war. This knowledge was first passed to him by Ambrose of Milan, which he developed in The City of God as rules for Christian's response in times of war. The research covers the period between 2000 - 2015, although some other earlier and latter dates may be included as a matter of emphasis. The scope of the study covers North Eastern Nigeria.