Victory,
Islam is generally seen by some non-Muslims, as a threat, because of several reasons, such as:

1. Most of the violence worldwide is done in the name of that religion.

2. Contrary to most of other religions that are mostly kept private and are seen as the relation between the individual and god, respecting each individual’s degree of commitment or even non commitment, Muslims feel the need to display their religion’s commitment. Not only they feel the need to display but to measure and judge others. This causes a tremendous pressure on the individual who struggles between what he practices and what he wants or feels need to show. This stimulates moral policing (rejected by human nature, particularly by non Muslims in general) and defensive and protective modes which result in hypocrisy.

3. The Koran does incite violence against the “enemy” that is why the extremists think that they are doing the right thing.

4. On the other hand, even knowing that those extremists are a minority, the majority of good Muslims don’t voice their views in public against Islamists. Leaving the impression that they consider "Infidels" worse than "Islamists".