[Looking for Diogenes]

America was founded as a non-sectarian Christian country.

I have no doubt that most, if not all, of the Founders were Christians. I also have no doubt that they did not found a Christian nation. There is no single quotation which you have provided, by Washington, Adams, Hamilton or Rush, which states otherwise.

This one comes close:
"It is rightly impossible to govern the world without God and the Bible." --George Washington

However there is no record that Washington ever said it. It's a pity that you have to resort to misquoting Washington to try to make your point.

Unconfirmed Quotations

[rmlew]

I have no doubt that most, if not all, of the Founders were Christians. I also have no doubt that they did not found a Christian nation. There is no single quotation which you have provided, by Washington, Adams, Hamilton or Rush, which states otherwise.
All of the above made it clear that America was to be a religious nation. All were Christians. What religion do you think they were talking about? Hale Bop...?

However there is no record that Washington ever said it. It's a pity that you have to resort to misquoting Washington to try to make your point.
At worst it is an unConfirmed quote, in line with Washington's general beliefs.
I did not originate the quote. I got it from the bi-weekly publication, The Federalist.