I believe we have to keep in mind that the moral standards established by Christ are very high and we fall far short of living up to them.  He called upon us to love one another with the same love he has for us which is the love the Father has for him.  We will never achieve that goal, but we must ever strive to make progress in that direction.  War, while we have not found ways to avoid it, should always be the last resort and  should always  be a reminder of how far we are from reaching the ideals placed before us by Christ.  It is a constant reminder of the failure of Christianity.