There were Rabbinites and Karaites in Iraq at the the time of Sa'adia Gao. During the time of Maimonides there were Yemenite Jews that were forced to become Moslems and asked him how to deal with it. After Shabtai Tzvi converted to Islam, ever some time before, there were Rabbinical and Communal leaders that condemned that new sect of Jews for the next two centuries and Shabta'ut was declared a heresy. We all know the struggles between the Chasididm and Mitnagdim and what that fight was conducted--that wasn't nice either. Now we have another set of disputes. Come Tisha b'Av it's time to learn that trashing each other, whether its the WOW and the extremist Charedim, or the "Modern Orthodox" and the less stringent Modern Orthodox, or however it's sliced. It's no good for anyone..
Woman moderately wounded by firebomb thrown at her car in north J'lem (Haaretz)
from the article: Shas leader: Modern Orthodox in Israel is Amalek - enemy of the Jews