Returning to the central issue, though...
AT BEST you can claim, SC, that Jefferson's views are in dispute.
At worst (for you) my claim of his being an admirer of Jesus' teachings and theologically a deist and NOT a Christian under the standard understanding of that term holds.
AND...
We could do this for all the Founders if we so wished.
And likely run up against the same arguments.
The fact then is that, at best, you can claim the Founders' views to be in dispute, and at worst, for you, you must concede that a great many (Paine and Franklin most glaringly, and there's a strong case for Jefferson as well, to say nothing of Madison, Washington, Adams, or the others) were, in fact, deist and not Christian...
And thus the argument holds that they were NOT Christian.
They were not Christian...
The Constitution is not Christian...
The laws of this country are not Christian...
The VALUES of this country are not Christian (they are Western, to be sure, but saying values such as honesty, charity, compassion, liberty, and so on are all "Christian" values implies that they are somehow Christian and only Christian, and that the Jews, Muslims, Buddhists, atheists, and so on that make up a larger and larger swath of this country don't hold those views and values, which is insulting and completely untrue--these are UNIVERSAL values--and if that's not what you mean, and mean only that these are Christian values and that the above groups share them as well, then what need is there to call them "Christian values" at all when they are not specially "Christian," why not "Western" or even just "American" values...even "Human Values" works fine--I think most human beings, West, East, Christian, Muslim, Jew or Atheist will endorse charity, freedom, compassion and all those other values, after all...Christianity has no such monopoly over these...)
As such, to call America a "Christian Nation" on these grounds is absurd.
I agree with you, SC, that to even TRY to call America a Christian Nation on these grounds is a poor argument to begin with, but even in the context of that poor argument, the argument is a failed one, through and through.
And with that...time for bed at 8am. Hooray for Saturdays. :)