Darrell Cole writes in the Spring, 1999 issue of the Journal of Religious Ethics:
[W]hat is surprising to the modern reader, even the modern Christian reader, is the prominence [Aquinas] gives the virtue of charity in his discussion of the violence of war. Aquinas’s logic, however, is impeccable; charity is the virtue necessary for acquiring all other virtue and, hence, for acquiring excellence in any worthy practice. Love and war are not incompatible, and to be morally acceptable, warmaking must be a work of love. This means that a soldier cannot be an excellent soldier qua Christian soldier without charity.
So, a soldier must love the ones he kills? Large-scale destruction of property, infrastructure, and human life is an act of love rather than hate? When you kill in the name of love, it’s so much easier to justify and excuse — hate, after all, implicitly negative and therefore difficult to rationalize. When you act out of love, however, almost anything may be permitted.
In a just war, the Christian fights for charity’s sake and therefore fights under the guidance of the moral arche of the ultimate end. Because Christians fight such wars under the virtue of charity, they do not fight in order to secure the goods of peace and order for themselves, but rather for their country, family, and friends.
If we push Aquinas’s logic to its conclusion, we can say that the soldier who fights for charity’s sake is actually engaged in a kind of acting that unites him to God; for charity is that virtue for Aquinas that, as Romanus Cessario states, engages the believer with “everything worthy of authentic Christian love” (Cessario 1991, 96). The lesson is clear: fighting just wars is an act of charity, worthy of Christian love, that unites the believer to God.
So, large-scale destruction of property, infrastructure, and human life isn’t just an act of love, it’s an act of unity with God — and I guess God loves the destruction of human life in the name of charity and love, right? What monstrousness can’t be justified by saying that it unites a person with their god?