As the story goes, someone asked Hamilton why the Constitution didn’t include any references to God. Hamilton, apparently doing his best Bob Newhart impression, responded “We forgot.”
They didn’t, of course. The 1787 iteration of the Constitution was a document intended to define and allocate power, not a philosophical statement. And, notwithstanding what the current crop of “constitutional conservatives” say, it was an effort to enhance federal power relative to the Articles of Confederation; if the Founding Fathers’ primary concern had been to limit federal power, the Articles already did that quite nicely.
The religious right typically makes the argument for a “Christian” version of the Constitution based on language in the Declaration of Independence. That is an erroneous interpretation, for reasons I will discuss tomorrow. For present purposes, the point that needs to be made is that, even if you accept the religious right’s view of the Declaration, it is legally inappropriate to use the Declaration to interpret the Constitution, for the following reasons:
1. The two documents were written by different people. For example, Hamilton and Washington were in the Continental Army at the time of the Declaration, while Jefferson was in France during the Constitutional Convention.
2. The two documents were written for different purposes. The Declaration was a piece of wartime propaganda that was intended to justify the Revolution, while the Constitution obviously sets up a completely new system of government.
3. The two documents were were written at different times. The Constitution was written after the war and the experience with the Articles, which undoubtedly had an impact on the mindset of the delegates.
4. The Constitution was ratified; the Declaration was not. As a result, the opinions of plenty of people outside of the Convention itself are relevant in interpreting the Constitution.
The bottom line is that it was appropriate for Lincoln to make the broad, philosophical argument that the Constitution was a first and imperfect step in the realization of the ideals inherent in the Declaration, but from a purely legal perspective, using the Declaration to interpret the Constitution is a mistake. The Constitution is in no way a “Christian” document; it owes more to Plato and Aristotle than to St. Paul.