How they penetrated security is not relevant. The attack was creative enough, audacious. But how they co-ordinated their efforts on such a grand scale is unimaginable. The creativity, the discipline, the very passion so rigorously harnessed towards their mighty goal is superhuman. If what they had done had delighted us (as it probably has done their supporters), it would have been a magnificent work of art.
But that all this discipline, planning, organisation was entirely directed at taking human life means that its power can come only from the Devil. Their work is so evil that it can only be done by the inhuman.