I often use the phrase "historic Christianity" to denote longstanding traditional orthodox Christianity. Note this tradition goes back thousands of years; if something occurred in Christendom, for instance, 150 years ago, I consider it relatively “novel” looking back at the big historical picture. I also understand there is a long tradition in Christianity of heresy and dissent (prompting orthodox Christians to reply: “This isn’t ‘historic Christianity’"). And I have no personal problem with theologically liberal, unorthodox and heretical faiths (indeed were I to become a Christian it would probably be that kind; and then the orthodox could tell me, "no, you really aren't a Christian").
I especially try to remove 20-21 Century, and even late 18th Century cultural "prejudices" when examining "historic Christianity." Doing so permits me to conclude that much of what the American Founders claimed to do under the auspices of Christianity is either incompatible with such, or, at the very least had an alien origin. For instance, Locke's a-biblical, perhaps anti-biblical notion of the "state of nature" was preached from Christian pulpits during the Founding era to justify revolt. Similarly, today the Christian pulpit might lecture on the need for "self-esteem," which is either a) anti-biblical (I thought Christians were supposed to despise themselves as wretched sinners) or b) at the very least, not of "biblical" origin and thus, not part of "historic Christianity."
[American Creation Readers: I am going to direct you to the rest of the post at Positive Liberty; I'm doing so because I don't want to be a "space hog" and blogger doesn't allow for hiding portions of your big posts! But feel free to discuss the contents here.]