Originally Posted by al_imaan_786
I think it's generally understood that terrorist action is not sanctioned by authoritative Islamic teachings, but it's easy to see why people might be under the impression that it is.
The attacks carried out in New York, Bali, Madrid and London were committed by people who claimed that they were doing the work of Allah, and who appeared genuinely to believe that their work was furthering the cause of Islam.
Those Christians who committed terrible acts of destruction in WW2 and Northern Ireland did not claim that they were working from a religious motivation, nor did they claim that they were performing a Christian duty. The Crusades, on the other hand, are a good example of Christians behaving in a savage way in the name of their religion.