Ignorance...and the media does not help...
I do an activity in my classes, before we begin our study of religions....where they have to get out a sheet of paper and pen. I write a word up on the board and they are to right the first thing that pops in their head...and then we share them. Of course before lunch I get, tacos, hamburgers, all kids of stuff, but for the most part they play along.....the first word I put up is "Islam"....I get, raghead, 7-Eleven, terrorism, oil, theocracy, death, Muhammad, Quran, mosque, Iraq, Iran, etc....most are negative.
Then I put up the word Christian, I get....United States, Baptist, Methodist, Catholic, pretty much all of the Christian religions, Jesus, white man (yes, I get white man), preacher, priest, God, communion, church, mass, mostly positive, but I have gotten, hypocrisy before...I was very intrigued by that answer, come to find out, this student was agnostic...
Then we compare the negative to the positive of each religion, and I ask them where they learned these things about each religion. For Islam, they said, #1. the internet, #2. TV, #3, church, #4. school.... Where they learned about Christianity, they said, #1. church, #2. family, #3. friends, #4 media.
I will say this.....over the past 12 years that I have been doing this activity, the negatives for Islam, have decreased each year...