Injustice is a greater evil than war, according to St. Augustine, and it is proper to carry out a lesser evil if it would prevent a greater evil.
"War is hell," said Union Gen. William Tecumseh Sherman during the U.S. Civil War, "You don't know the horrible aspects of war."
The Sixth Commandment, "Thou shalt not kill," that Christians and Jews alike understand to be God's law, is a non-negotiable. There is no equivocation for violence that would cause the intentional destruction of innocent human life. Some Protestant denominations have used this commandment to claim there can be no justification for war and have refused to serve in the military during wartime.
Augustine believed that war was always the result of sin, of an evil so heinous to God's plan for life. But he said war was also the remedy for sin and therefore it could be justified. So, the question in looking at Israel's war on Hamas is if those waging it do so with the intention of doing good. Punishing the enemy, which is what many feel would be justified, is not a sufficient motive on its own, according to Augustine. Vengeance or revenge should not be the motive.