Amongst the ignorant and fearful, I would imagine the main reason that muslims are distrusted and hated to be the fact that in recent times, people who identify as muslim have brought catastrophic death and destruction to innocent men, women, and children in every corner of the world.
9/11, Bali bombings, 7/7 attacks, Madrid train bombings, Beslan hostage crisis, Toulouse shootings, Benghazi diplomatic mission attack, the list goes on and on.
Your law abiding muslim minding his own business in the street is almost a victim of these attacks in his own right, as the way the media reports these tends to whip the ignorant and fearful into a frenzy. This is when he becomes "the enemy" by association.