The ACLU says they fight for civil liberties, and that they do, for the Klan or for students' rights (though they're hardly perfect; they had a shameful period of collusion with the FBI). The People For The American Way has the neutral-sounding name of the interest group.
The ACLU fights Chrisitianity in the schools and the "public square" but does not challenge the teaching of Islam in public school curriculum (even including the reading of Islamic prayers) nor did they voice in on the request for a city to permit and amplified prayer call 5 times a day from a mosque in Michigan.