The Fifth Commandment forbids the intentional destruction of human life. Because of the evils and injustices that accompany all war, the Church insistently urges everyone to prayer so that the divine Goodness may free us from the ancient bondage of war (CCC 2307). Thus, all citizens and all governments are obliged to work for the avoidance of war (CCC 2308).
The legitimate defense of persons and societies is not an exception to the prohibition against the murder of the innocent that constitutes intentional killing. The act of self-defense can have a double effect: the preservation of one’s own life; and the killing of the aggressor…The one is intended, the other is not (CCC 2263). However, the Fifth Commandment forbids doing anything with the intention of indirectly bringing about a person’s death without grave reason (see CCC 2269).
Unintentional killing is not morally imputable. But one is not exonerated from grave offense if, without proportionate reasons, he has acted in a way that brings about someone’s death, even without the intention to do so (CCC 2269).
Legitimate defense cannot only be a right but a grave duty for someone responsible for another’s life (CCC 2265). Preserving the common good of society requires rendering the aggressor unable to inflict harm (CCC. 2266). The strict conditions for legitimate defense by military force require rigorous consideration. The gravity of such a decision makes it subject to rigorous conditions of moral legitimacy. At one and the same time:
1. The damage inflicted by the aggressor on the nation or community of nations must be lasting, grave and certain;
2. All other means of putting an end to it must have been shown to be impractical or ineffective;
3. There must be serious prospects of success; and,
4. The use of arms must not produce evils and disorders graver than the evil to be eliminated. The power of modern means of destruction weighs very heavily in evaluating this condition.
These are the traditional elements enumerated in what the Church calls the “Just War” doctrine (see CCC 2309). This doctrine was first introduced by St. Augustine in the fourth century, and later refined by St. Thomas Aquinas in the Middle Ages.
Note well: “Just War” is war undertaken only to repel an aggressor. It is not undertaken as a “pre-emptive” measure or as a means to impose a system of government upon another nation. Such reasons cannot possibly meet the rigorous criteria of the Just War doctrine. Moreover, acts of war directed to the indiscriminate destruction of cities or vast areas with their inhabitants is a crime against God and man, which merits firm and unequivocal condemnation (CCC 2314). Since modern weapons are able to bring about such devastating effects, it is extremely difficult to justify war in the 21st century. In fact, St. Thomas More said the same thing in the early 16th century.
Many Christians refer to the following verses which show God’s opposition to war:
Matt. 5:9 – Jesus says “Blessed are the peacemakers, for they shall be called sons of God.”
Matt. 5:39 – Jesus says “Do not resist one who is evil. But if anyone strikes you on the right cheek, turn to him the other also.”
Matt. 5:44 – Jesus says “Love your enemies and pray for those who persecute you.”
Matt. 26:52 – Jesus says that whoever takes the sword will perish by the sword.
Rom. 12:17,21 – Paul says “repay no one evil for evil, but take thought for what is noble in the sight of all. If possible, so far as it depends upon you, live peaceably with all. Do not be overcome with by evil, but overcome evil with good.”
Job 5:20 – the Lord redeems those in war, from the power of the sword.
Isaiah 2:4 – “They shall beat their swords into plowshares, and their spears into pruning hooks; nation shall not life up sword against nation, neither shall they learn war any more.”
Psalm 27:3 – war is unnatural, and we must put our confidence in the Lord.
Psalm 33:17 – the war horse is a vain hope for victory.
Psalm 46:9 – the Lord makes wars cease to the ends of the earth, breaking the bow, shattering the spear, and burning the chariots with fire.
Psalm 55:21 – those who have war in their hearts are deceptive and evil.
Psalm 68:30 – the Lord tramples people underfoot, those who delight in war.
Psalm 140:2: the Lord condemns those who plan evil and stir up wars.
1 Chron. 22:8; 28:1; 2 Chron. 14:6;Mic. 2:8; 4:3; Judt. 9:7; 16:3; Hos. 1:7; 2:18; Jer. 42:14 – more examples of God’s opposition to war.
While these passages emphasize God’s desire to avoid war and conquer evil with good, nothing in Scripture says that legitimately defending oneself or one’s country which results in the killing of another is an intrinsically evil act. Following are some of many Scriptures which support this view (and there are many other passages in Scripture where God sanctions, and even orders war):
Gen. 15:14-21 – God blesses Abram through the priest-king Melchizedek after Abram’s war victory over Chedorlaomer and his cohorts. Melchizedek offers a bread and wine sacrifice in thanksgiving for Abram’s victory and Abram gives Melchizedek a tenth of the spoils.
Ex. 15:3 – “The Lord is a man of war, the Lord is his name.”
Deut. 1:41; 20:1,12,19-20; 21:10; Jos. 6:3; Joel 3:9 – some examples where the Lord commands war when the reasons are justified.
Prov. 20:18 – “Plans are established by counsel; by wise guidance wage war.”
Num. 1:3-45; 21:14; 26:2; 31:3-53; 32:6-27; Jos. 4:13; 10:5,7,24; 11:7,18,23; 14:11,15; 17:1; 22:12,33; Judges 3:1-2,10; 18:11,16-17; 20:17; 1 Sam. 8:12; 16:18; 17:20; 18:5; 19:8; 23:8; 2 Sam. 11:7; 22:35; 2 Kings 18:20; 24:16; 25:4,9; 1 Chron. 7:2-40; 8:40; 12:1-38; 2 Chron. 26:13; Prov. Job 38:23; Psalm 18:34; Cant. 3:8; Jer. 39:18; 45:5; Judt. 5:1; Dan. 11:10; Wis. 8:15; Sir. 46:3; Bar. 3:26 – more Old Testament examples where God approves of war.
Matt. 8:5-13 – Jesus praises a Roman centurion warrior for his faith and cures the centurion’s servant. Jesus would not have responded to the prayer of an evil man unless it was a prayer of repentance. Obviously, although the centurion was a soldier, Jesus did not consider him an evil man, but a very faithful man, even more faithful than anyone else in Israel.
Luke 14:31 – Jesus acknowledges the legitimacy of war in this parable.
Luke 19:27 – Jesus says “But as for these enemies of mine, who did not want me to reign over them, bring them here and slay them before me.” Jesus teaches that not all killing is intrinsically evil.
Luke 22:36 – Jesus says “let him who has no sword sell his mantle and buy one.” Jesus encourages the legitimate defense against an aggressor.
Acts 10:2 – God responds favorably to another centurion’s prayer (Cornelius of the Italian Cohort), even though he was a soldier. The soldier’s “prayers and alms ascended as a memorial before God.”
Heb. 11:32-34 – Paul praises Gideon, Barak, Samson, Jephtha, David and Samuel who conquered kingdoms, enforced justice, became mighty in war and put foreign armies to flight. These men engaged in the legitimate defense of the people of God and were praised for their faithfulness.
Rom. 13:3-4 – Paul commends us to those in authority, and exalts a man who “does not bear the sword in vain.” Paul calls such a man “the servant of God to execute his wrath on the wrongdoer.”
2 Cor. 10:3-4; 1 Tim. 1:18; Heb. 11:34; James 4:1; 1 Peter 2:11; Apoc. 2:16; 11:7; 12:7; 17:14; 19:11,19 – these New Testament passages reveal that the real war to be won is the spiritual war against the flesh and the devil.
Eccl. 3:3– the inspired writer says that there is “a time to kill.” We look to the Church, the pinnacle and foundation of the truth (1 Tim. 3:15) to understand when such a time exists. As we have seen, in the context of military action, this time exists only when it is: necessary to repel an aggressor; all other means of repelling the aggressor have been ineffective; there is serious prospects of success; the damage inflicted by the aggressor is lasting, grave and certain; and, the evils and disorders produced by the war must not be graver than the evil eliminated, that is, the act of defense must be proportionate to the aggressor’s offense.
Our country has had no such “time to kill” in recent memory, notwithstanding her actions to the contrary.