It's very common to see Christian Nationalists use the term "Judeo-Christian" to describe practices, traditions, and customs which they want to preserve as legal and state-endorsed, but which are indisputably religious in nature. The primary purpose of the term seems to be to deflect the obvious criticism that the practices and traditions are specifically Christian in nature; if they can be portrayed as involving more than just Christianity, then perhaps they won't be seen as promoting just one religion over all others. Does it work, though?

Cheryl writes:

The United States of America was founded on Judeo-Christian principles. We celebrate holidays that are Judeo-Christian, and predominantly Christian. If anyone is opposed to that, he or she is free to leave our country and go to a country that more adequately conforms to their beliefs and practices.

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Usually it is claimed that America is founded just on Christian principles and not many try to argue that there is anything Jewish about the legal or philosophical principles upon which the government of the United States is based. This is one area there really isn't an effort to make things ecumenical — I guess Christians who try to claim this aren't interested in sharing the credit? Regardless, there is no more basis for saying that America is founded on "Judeo-Christian principles" than saying that it is simply founded on "Christian principles."

More interesting, in my opinion, is the attempt to say that America celebrates "Judeo-Christian" holidays. I've never seen that before. There's obviously nothing Jewish about secular holidays like Independence Day or Memorial Day, but even traditionally religious holidays like Easter and Christmas aren't in any way Jewish. At least Cheryl had enough self-awareness to admit that the holidays are predominantly Christian, but I still have to see this as an example of serious overreach when it comes to denying the exclusively Christian character of traditional religious practices in America.

It's not a coincidence that this comment was made in response to an article about problems with fitting in some sort of recognition of Ramadan holidays in public schools. American schools almost always make allowances for Christian holidays and usually do the same for Jewish holidays, but giving Muslims equal treatment is giving some Christians fits. They don't want to treat Muslims as fully equal, but they also don’t' have any legal or moral basis for not doing so.