is unbecoming for
them to slay or shed blood, and it is more fitting that they should
be ready to shed their own blood for Christ, so as to imitate in deed
what they portray in their ministry. For this reason it has been
decreed that those who shed blood, even without sin, become
irregular. Now no man who has a certain duty to perform, can lawfully
do that which renders him unfit for that duty. Wherefore it is
altogether unlawful for clerics to fight, because war is directed to
the shedding of blood.

Reply Obj. 1: Prelates ought to withstand not only the wolf who
brings spiritual death upon the flock, but also the pillager and the
oppressor who work bodily harm; not, however, by having recourse
themselves to material arms, but by means of spiritual weapons,
according to the saying of the Apostle (2 Cor. 10:4): "The weapons of
our warfare are not carnal, but mighty through God." Such are
salutary warnings, devout prayers, and, for those who are obstinate,
the sentence of excommunication.

Reply Obj. 2: Prelates and clerics may, by the authority of their
superiors, take part in wars, not indeed by taking up arms
themselves, but by affording spiritual help to those who fight
justly, by exhorting and absolving them, and by other like spiritual
helps. Thus in the Old Testament (Joshua 6:4) the priests were
commanded to sound the sacred trumpets in the battle. It was for this
purpose that bishops or clerics were first allowed to go to the
front: and it is an abuse of this permission, if any of them take up
arms themselves.

Reply Obj. 3: As stated above (Q. 23, A. 4, ad 2) every power, art or
virtue that regards the end, has to dispose that which is directed to
the end. Now, among the faithful, carnal wars should be considered as
having for their end the Divine spiritual good to which clerics are
deputed. Wherefore it is the duty of clerics to dispose and counsel
other men to engage in just wars. For they are forbidden to take up
arms, not as though it were a sin, but because such an occupation is
unbecoming their personality.

Reply Obj. 4: Although it is meritorious to wage a just war,
nevertheless it is rendered unlawful for clerics, by reason of their
being deputed to works more meritorious still. Thus the marriage act
may be meritorious; and yet it becomes reprehensible in those who
have vowed virginity, because they are bound to a yet greater good.
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THIRD ARTICLE [II-II, Q., 40, Art. 3]