Because "Judeo-Christianity" doesn't exist of course. The term is a neologism, more specifically a retronym, where the old term loses its meaning and needs a qualifier to make any sense. Like "acoustic guitar." Once upon a time, all guitars were acoustic, like before electricity and before Les Paul invented the electric guitar.
Note how guitars are now pointed upwards, but in the olden days, they were always horizontal. That's just the least of the differences, but this illustration do for now.
Anywayz, way back when, there were yr Jews and there were yr Christians, and never the twain should meet, least of all in a hyphenated word. Might as well call Thomas Jefferson a "Democrat-Republican"! But today, necessity dictates the miscegenation of "Judeo-Christian" in trying to make some sense out of the religious landscape at the founding of this here US of A.
You see, our first four or five presidents believed in the Bible more or less, but didn't believe Jesus was God or died for our sins or is the Second Person of the Holy Trinity, whatever that is. But they believed that the Bible wasn't total bunk and that man was created in God's image like it says in Genesis 1:26 and Genesis 9:6.
That meant that man was endowed by his Creator with certain unalienable rights, blah, blah blah. But it was still a statement that the human race, for all its intellectual fortitude, hasn't managed to get around yet. Whether truth, myth, or illusion, the idea founded the greatest nation in history [IMO], and is imitated around the world through the present day.
I was struck by something the atheist Jürgen Habermas [who was one of the philosophical founders of post-WWII Europe] wrote recently:
Christianity has functioned for the normative self-understanding of modernity as more than a mere precursor or a catalyst. Egalitarian universalism, from which sprang the ideas of freedom and social solidarity, of an autonomous conduct of life and emancipation, of the individual morality of conscience, human rights, and democracy, is the direct heir to the Judaic ethic of justice and the Christian ethic of love. This legacy, substantially unchanged, has been the object of continual critical appropriation and reinterpretation. To this day, there is no alternative to it. And in the light of the current challenges of a post-national constellation, we continue to draw on the substance of this heritage. Everything else is just idle postmodern talk.---Jürgen Habermas, “Conversation About God and the World,” Time of Transitions, (Cambridge: Polity Press, 2006): pp. 150-151.
Ah. Judeo-Christianity. At last.
Now, intellectual honesty would oblige Jürgen Habermas to deny that Jesus is God or even that the Old Testament [another retronym, eh?] is revelation from God. Or that God even exists. Still, Habermas, a manifestly good man, can't get around that ol' Bible, which had certain unique ideas. "Judeo-Christianity" sums up those ideas, justice, and then on to love [which I read as mercy].
I think the Founders, even the first four presidents, were cool with that. Were they "Christians?" Nah. Were they Jews? Hah! "Judeo-Christians?" Mebbe.
[Oh, BTW, Jefferson always seemed quite in accord with rabbinical Judaism to me. No Jesus-is-God, emphasis on good works. Turns out he WAS Jewish!]
Cross-posted @ American Creation.