For years, the American Civil Liberties Union (search) and other groups have fought to remove any trace of religion from government and public life, and for years they've won.
Now the ACLU is facing a challenge from groups such as the Alliance Defense Fund (search), one of several Christian law firms formed in the 1990s.
From its base in Phoenix, the ADF says its goal is to defend religious liberty, the sanctity of human life and the traditional family against any person or group who attacks those principles.
"The ACLU has through the years filed a series of lawsuits that diminish the rights of Americans to understand their history, to exhibit in public, to exercise their faith in many ways," said ADF president and CEO Alan E. Sears (search).
In one of its better-known cases, the ADF sued the city and county of San Francisco and successfully argued before the California state Supreme Court that marriage licenses granted to same-sex couples should be declared null and void because the mayor and county clerk did not have the authority to issue them.
Now it's working on what it calls its "Christmas project," an effort to defend school districts around the nation against lawsuits to ban Christmas trees and other religious displays during the holidays.
Former ACLU board member Susan Estrich (search), a FOX News contributor, said groups such as the ADF are unnecessary because they represent a majority group, which already has all the influence it needs.
"So long as Christians are voting and electing the majority, and the majority of our leaders are Christian and the majority of our judges are Christian, I'm not sure who the Christians are ultimately complaining about," Estrich said.
Of course, it only takes one person to file a lawsuit. In San Diego, a single atheist has kept the city in court for over a decade trying to get a cross removed from a war memorial. The ADF and their allies say that's why they exist.
Click in the video box above to watch a full report by FOX News' Anita Vogel.