"Our nation was founded on Judeo-Christian values and principles."
Despite what many say, the US was not founded on Judeo-Christian values. If it was founded on any religious values, it was purely Christian ones.
The term Judeo-Christian has a benign history. It was popularized by liberal groups in the 1920s and 1930s to forestall anti-Semitism. But it has nothing to do with the history of the founding of the US.
Liberals repeatedly whining about this is not convincing to most people, so perhaps you'll listen to the US Supreme Court.
The case is Van Orden v. Perry (2005). It involved a privately donated Ten Commandments display (see photo above) situated on the grounds of the Texas State Capitol (public property). The Supreme Court upheld the display as sufficiently secularized by the 21 other monuments, both secular and religious, scattered throughout the grounds.
Part of the reasoning was that the Founders themselves approved of the display of the 10 commandments in a variety of settings, and thus the Constitution must mean to allow for this kind of display.
I want to focus your attention on this passage from Justice Stevens' dissent:
Many of the Founders who are often cited as authoritative expositors of the Constitutions' original meaning understood the Establishment Clause to stand for a narrower proposition [than what the court holds]. Namely, many of the Framers understood the word "religion" in the Establishment clause to encompass only the various sects of Christianity. [Justice Scalia's] inclusion of Judaism and Islam is a laudable act of religious tolerance but it is one that is unmoored from the Constitution's history and text and moreover one that is patently arbitrary in its inclusion of some, but exclusion of other (e.g., Buddhism), widely practiced non-Christian religions.
Basically, Stevens is saying, "Are you kidding me? If you're going to interpret the Constitution like the founding fathers meant, then be honest about the fact that there was no "Judeo" involved here. It was all just "Christian.""