1. The Constitution is not a religious document.
2. The Constitution is not an anti-religious document.
3. The Constitution includes more than the founding.
Read the entire piece at the Daily Beast to see how he develops these points.
Here is an interesting section on the phrase "in the Year of our Lord":
One textual arrow might seem to point in a different direction. Immediately preceding the thirty-nine famous signatures at the bottom of the 1787 parchment, we find the following words: “done in Convention by the Unanimous Consent of the States present the Seventeenth Day of September in the Year of our Lord one thousand seven hundred and Eighty seven and of the Independence of the United States of America the Twelfth. In witness whereof We have hereunto subscribed our Names.” [Emphasis added.]
At first blush, these words might seem to contradict the central meaning of the religious test clause and the presidential oath clause. After all, the Constitution requires federal officials to take an oath to the Constitution itself. If that document really does proclaim that Jesus Christ is “our Lord,” then isn’t this oath-taking itself an improper religious test?
As it turns out—though this fact has until now not been widely understood—the “our Lord” clause is not part of the official legal Constitution. The official Constitution’s text ends just before these extra words of attestation—extra words that in fact were not ratified by various state conventions in 1787-88.
What, then, are we to make of these words? Just this: The words “our Lord” are much like the words “so help me God” in presidential inaugurations. No president can be obliged to utter these words in his inauguration ceremony, but presidents may choose to add them, if they wish. Over the course of American history, many presidents (and most modern presidents) have in fact chosen to add these words. Similarly, the Constitution nowhere requires a president to swear his oath of office on a Bible, but a president can choose to do so—and almost all presidents, beginning with George Washington, have in fact done so. Similarly, the thirty-nine framers at Philadelphia were allowed to profess their faith even in the public square. Some signers with quill in hand likely gave no thought to the “Year of our Lord” language and its theological overtones. But other signers may well have mused on things eternal, and on their personal relationships to God, at the precise instant when they added their names to a plan that they hoped would sharply bend the arc of human history toward justice. All of which leads us to our next general principle:
HT: Jon Rowe at American Creation