I wouldn't be please if killers came but I would still encourage my children to read what they might give them. You may be afraid your children can't handle different ideas but I think that it is very wrong to block them from it.
That said, what exactly about Christian principles in the bible gives you equal concern with the terrorist's principles in removing the Israel and the great satan (the US) from the face of the earth? Even my 11 year old could make the distinction, can't you?