By all accounts — starting with the Gospels — the crucifixion was a brutal affair, during which Jesus Christ was tortured, nailed to a wooden cross, taunted, and left to die a slow and painful death. (It’s where we get the word excruciating.) The event has been recreated countless times since, in painting and sculpture, celluloid and “South Park.” It might be the most common theme in all of Western art. The image is so iconic, in fact, that many of us had probably grown somewhat numb to the bloody savagery it represents, at least until the Islamic State revived the practice.