Why are muslims looked down on all the time?

I am a muslim. This year I’m an atheist. Well, I was born a muslim and I’m from a muslim country. But I don’t wear headscarf, and none of my friends do. We party, drink, hangout, hook-up… Our education is really good… But every time I used to say I’m a muslim in america, they would look at me in a disgusting way and discriminate me. How can you look at one religion as just one type of group and talk according to that? Honestly, when I think of jews I think of my friends who are not dressed funny and braid-bearded. But I also know that there are very religious people in each religion.
I think it is so ignorant to say muslims are terrorists, and that they can’t even see boys, etc. It makes me sad and confused.