The First Amendment to the United States Constitution prohibits Congress from the making of any law respecting an establishment of religion, IMPEDING THE FREE EXERCISE OF RELIGION...(and) INTERFERING WITH THE RIGHT TO PEACEABLY ASSEMBLE...
Atheists, as individuals and collectively, seek to deprive other religions from freely practicing their religions thus violating the religious "civil rights" of others.
The Establishment Clause 'free exercise clause' accommodation interpretation prohibits Congress from preferring one religion over another, but does not prohibit the government's entry into religious domain to make accommodations in order to achieve the purposes of the Free Exercise Clause.
Organized Atheism violates the spirit of religious freedom and undermines traditional values.