I prefer Mohammedan because it signifies "follower of Mohammed" as in "follower of Mohammed, not God." Besides, they don't like it.
Mu·ham·mad·an Pronunciation Key (m-hm-dn) also Mo·ham·med·an (m-) adj.
1. Of or relating to Muhammad.
2. Offensive. Of or relating to Islam; Muslim.
n. Offensive
A Muslim.
Hey, I didn't know that!
I thought it would have been the equivalent of calling someone a Lutheran, Calvinist, or Wesleyan. Now that I know, I will use the term more regularly, along with "infidel" (a personal favourite) and "Saracen dog".