Separationist groups such as the ACLU say they get involved in the issue only if they get a complaint.
From the washingtonpost.com
Jeffries and Ryan argue that no-aid position drew support from a coalition of separationist opinion.
From the en.wikipedia.org
Whitehead says his views have made him an outsider among Christian and separationist civil liberties litigators alike.
From the washingtonpost.com
More examples
Separatist: an advocate of secession or separation from a larger group (such as an established church or a national union)
(separationism) advocacy of a policy of strict separation of church and state
Separatism is the advocacy of a state of cultural, ethnic, tribal, religious, racial, governmental or gender separation from the larger group, often with demands for greater political autonomy and even for full political secession and the formation of a new state. ...
(Separationists) Those who believe that the founders meant to erect a "wall of separation" between church and state, and, therefore, that government cannot aid religion, aid religiously motivated activities, or favor religion over irreligion.