Terrorism - a query

This bit I do not understand:
Two parts of the Koran
a) you shall not take your own life
b) you shall not take other lives
There are caveats about 'enemies', however.
Islamic Holy guys can decree who is an enemy , and this is how the troubles started, firstly with Israel [I'm leaving it open whether it pre 1967 /post or both] and then with Saudi clerics preaching the States was the Great Satan [years ago -but may have been until recently for all I know]

My query is this: if the clerics get it wrong and a muslim 'goes to war' and dies, what are the consequences for that guy in Koran terms- does he get 'acquitted' or is he damned ? Presumably the cleric gets his come-uppance ?

It might sound facile, but could raise a few queries in the mind of a potential terrorist.

HM government is planning to raise a few new laws on terrorism, namely planning/incitement . I still can't seem to find a true legal definition of a terrorist, though , so this law if it comes about is going to have a HUGE loophole in it for future uses...........