As Bishop Augustine knew back around AD 400, attending church and praising God is no assurance of virtue. Stalin had been a seminarian. As a boy, Hitler attended church and sang in the church choir. Putting a cross on the wall of the school at Littleton, Colorado, probably would not have made a difference. We should exercise restraint rather than allow our emotions free rein.
Unrestrained emotion can, in a flash, produce barbarity.
Victims need to be on guard against their own over-reactions. The Serbs have been victimized, and they became victimizers. So too with Kosovo Albanians. The Arabs made the Israelis more aggressive by aggravating them, and the Israelis have had their own over-reactions. In international politics, keeping commitments, standing firm and a willingness to act are needed along with restraint.