When police officers are shooting against bank robbers who have taken hostages, and the bank robbers start shooting the hostages, does that mean that police officers can send for the robbers families and then threaten their lives and kill them to deter the robbers?
We are muslims, and if non-muslims break their secular laws, that does not mean we break our holy ones. In Jihad we do not attack or deliberately harm non-combatants, that is what Islam has ruled on us. For our adversaries who commit a crime, we go and punish those specific people, we do not attack their families out of revenge.
Why were we making Jihad then in the first place if we will lower ourselves to their level and go massacre defenseless people? What good is it going to do for Islam when we build more hatred and give more ammunition to hate muslims, with our only defense becoming the childish vindictive "they did it first"? And most importantly how can we be fighting for Allah's sake when we are deliberately disobeying him?
No matter what they do, it just goes to show how criminal they are. Muslims do not respond to criminal injustice with equal criminal injustice. If Muslims wanted to truly make jihad anyway, the soldiers attacking us are out there in organized lines, we should defend against the combating troops, not pull cowardly acts that end up backfiring anyway in all ways, and use the excuse that they themselves did it. After all, they are disbelievers who do not believe in nor subscribe to eternal punishment in hell, such an excuse does not work for Muslims.
