Ok so the first thing here:
Do not call this thing a massacre. Do not call this a "time for grieving and vengeance". That's what they want.
Remember that. This is a time for remembering all who are lost and we shall not discuss the terrorists and their cause, because that is EXACTLY what they want. They want terror in the heart of western civilization; they want "non-believers" to crumble in fear of CIA (to them, the one true Caliphate). Radical Islamic terrorists want this -- all terrorists do.