Just war theory is the belief that war is morally or legally justified. There are four most important principles, also known as belief, principle or creed, derived from St. Augustine's just war theory. Saint Augustine was born in 354 AD and adopted the doctrine of Christianity in 386 AD during the decline of the Roman Empire. Saint Augustine believed that everything was made of God; therefore whatever is done is good and perfect. Saint Augustine believed that evil was due to the fall of man, which introduced sin into the world. Before the fall of man, there was no death, disease, or suffering in the world. Saint Augustine understood that war was the result of the fall of man and the introduction of sin into the world. Saint Augustine had accepted “war and violence as legitimate means of attacking subjective evaluations of evil” (Christophe p42). Saint Augustine had four important principles which are: “(1) There must be a just cause; (2) Wars must be declared and waged by the competent authority; and (3) The ultimate goal must always be peace. Furthermore, Augustine insists that soldiers must...