This reader describes the situation pretty well, I think:

The ADL seems to concentrate mostly on white, Christian anti-Semitism. I don’t think it’s necessarily a matter of political correctness. This is what the ADL was really formed to fight and that’s what it’s donors expect. But for every 90 year old Nazi or white separatist with six FBI agents watching him, there’re are tens of thousands of Muslims who live and breath vicious anti-Semitism. It would be a very large undertaking for the ADL to focus on the real anti-Semitism, it would mean becoming a whole new organization.