Their response will be that just because the insurgents are barbarians doesn't mean that we should lower ourselves to their level.
That is a debating technique called "framing the argument" in which we have to choose between being the barbarians or being civilized.
The opponents of the war have put us in this box and we have suffered casualties because of it.
War is brutal and savage, life and death judgments are made by young men under extreme duress.
The enemy often uses non combatants or religious sites as shields or traps.
We have to re frame the argument.
The enemy boobytrapped the dead (to be considered wounded) prisoners.
Where is Amnesty International? Where is Red Cross/Crescent? Where is the outrage?