I am a British Muslim and Imam based in London. I feel personally attacked by the brutal killing of this innocent person. My heart goes out to the family who has lost a loved one in such a tragic way. I extend to them my condolences and prayers. I am deeply sorry that Muslims have subjected you to this cruelty and pain. They have tarnished the entire faith and its followers.
A person using this defense of splitting will be vulnerable and possibly even seek out a group that has as its central mission, restoring him to the true Islam. At the same time, he could destroy the corrupted West - which may have become for him the symbol of his corrupted self, that he now wishes to disown.