The motive for the attack is yet unclear they say, well let met tell them;
The perpetrator, though he will be declared of unsound mind, will be a Muslim who, because he believes he has transgressed & will therefor spend eternity in hell, suffering among other things as stated in the Koran:
"...Those who deny (their Lord), for them will be cut out a garment of Fire. Over their heads will be poured out boiling water. With it will be scalded what is within their bodies, as well as (their) skins. In addition there will be maces of iron (to punish) them. Every time they wish to get away therefrom, from anguish, they will be forced back, and (it will be said), "Taste the Penalty of Burning!" (22:19-22).
"In front of such a one is Hell, and he is given, for drink, boiling fetid water" (14:16).
The only escape from this punishment is to become Muslim 'martyr' & the most assured way to accomplish this is to carry out the Fatwah which has been declared by some deranged anachronistic Muslim cleric.