At times like these it is important to remember that there are many, many different factions and sects of Islam, just like there are many sects of Christianity.
It would be wrong to attribute the actions of some radical Christian sect to all Christians. We would never confuse Latter-day Saints with Westboro Baptists nor Catholics with Branch Davidians. But we often fail to distinguish between Muslim sects. So we should be careful not to attribute the actions of some extreme Muslim sect to all Muslims. It is appropriate to condemn evildoing, but we must be careful not to apply our condemnation too broadly.