"See Reed v. Great Lakes Cos."
Judge Postner, "Title VII of the 1964 Civil Rights Act prohibits discrimintation against an employee based on the employee's religion, and even extends to an employee's "antipathy to religion." So even if Reed were an atheist, Title VII would provide protection if he in fact suffered discrimination as a result of his beliefs."
That is not saying atheism is a religion, it is saying it receives the same protections as one under the CRA.
The SCOTUS have also said "the Court has unambiguously concluded that the individual freedom of conscience protected by the First Amendment embraces the right to select any religious faith or none at all." (Wallace v. Jaffree)
But if having none at all was itself a religious faith, then surely that would read "any religious faith including none at all"?
So what of Kaufman v. McCaughtry, does it really say atheism is a religion?
"The Supreme Court has recognized atheism as equivalent to a “religion” for purposes of the First Amendment on numerous occasions, most recently in McCreary County, Ky. v. American Civil Liberties Union of Ky., 125 S.Ct. 2722 (2005). The Establishment Clause itself says only that “Congress shall make no law respecting an establishment of religion,” but the Court understands the reference to religion to include what it often calls “nonreligion.” In McCreary County, it described the touchstone of Establishment Clause analysis as “the principle that the First Amendment mandates government neutrality between religion and religion, and between religion and nonreligion.” [...] In keeping with this idea, the Court has adopted a broad definition of “religion” that includes nontheistic and atheistic beliefs, as well as theistic ones."
So no, it doesn't, it says atheism is a "religion", and defines a peculiarly broad definition of that word to accomodate their decision.
Note, under the definitions of "religion" used in the cases cited, agnosticism would also be a religion, as would "ignosticism" (not understanding or never having heard of the concept of gods). But if that were really the case then all preaching would have to be banned since I could not freely practice my "religion" of not knowing anything about gods with someone actively trying to "educate me".
So by all means define atheism as a religion under the SCOTUS definition. Then take down every mention of God, dismantle every church, recall every coin and note, change back the POA and remind everyone never to mention that word again, lest you infringe the ingnostics right not to hear it.