I find that these arguments are usually interminable until you actually define what you mean by the words "christian nation" as opposed to "nation of christians".
You can't separate the heritage of the US apart from Chrisitianity. That's very different however, than affording Christianity a special status and asserting that the nation was founded to give protected status to any one sect of Christianity or as has developed more since then, to the detriment or diminishing of other religious groups or individuals.
The principles upon which America were founded were to provide a framework that would guide and allow for adaptation as things changed. It was not to maintain a particular status quo in religion or culture through the power of the government.
The use of the word "Creator" in the declaration of independence ties both to the christian heritage and it was also common wording in the writings of Locke, Montaigne and other philosophers who influenced the underlying thoughts upon which it and later the constitution were founded. Deism did have influence. Remember that Deism is not Atheism. It's a belief in God but with the belief that God has given His children the power of thought and and based upon those things that were believed to be self-evident there was a strong desire to leave issues of religion to the state and to avoid any particular christian sect or even the establishment of mandatory non-religion.
While many of the founding fathers were christians, remember too that they were from different branches of christianity and also very fiercely committed to no-one usurping their own freedom. Until the war of 1812, most americans identified themselves more by the state they were a part of than the nation as a whole. That lessened after the war of 1812 but it still remained in place and didn't really completely pass until after the civil war.
Here's a list of the affiliation of the signers of the DoI from this site.
http://www.adherents.com/gov/Founding_F ... igion.html
Religious Affiliation of the Signers of the
Declaration of Independence
Religious Affiliation # of
signers % of
signers
Episcopalian/Anglican 32 57.1%
Congregationalist 13 23.2%
Presbyterian 12 21.4%
Quaker 2 3.6%
Unitarian or Universalist 2 3.6%
Catholic 1 1.8%
TOTAL 56 100%
Name of Signer State Religious Affiliation
Charles Carroll Maryland Catholic
Samuel Huntington Connecticut Congregationalist
Roger Sherman Connecticut Congregationalist
William Williams Connecticut Congregationalist
Oliver Wolcott Connecticut Congregationalist
Lyman Hall Georgia Congregationalist
Samuel Adams Massachusetts Congregationalist
John Hancock Massachusetts Congregationalist
Josiah Bartlett New Hampshire Congregationalist
William Whipple New Hampshire Congregationalist
William Ellery Rhode Island Congregationalist
John Adams Massachusetts Congregationalist; Unitarian
Robert Treat Paine Massachusetts Congregationalist; Unitarian
George Walton Georgia Episcopalian
John Penn North Carolina Episcopalian
George Ross Pennsylvania Episcopalian
Thomas Heyward Jr. South Carolina Episcopalian
Thomas Lynch Jr. South Carolina Episcopalian
Arthur Middleton South Carolina Episcopalian
Edward Rutledge South Carolina Episcopalian
Francis Lightfoot Lee Virginia Episcopalian
Richard Henry Lee Virginia Episcopalian
George Read Delaware Episcopalian
Caesar Rodney Delaware Episcopalian
Samuel Chase Maryland Episcopalian
William Paca Maryland Episcopalian
Thomas Stone Maryland Episcopalian
Elbridge Gerry Massachusetts Episcopalian
Francis Hopkinson New Jersey Episcopalian
Francis Lewis New York Episcopalian
Lewis Morris New York Episcopalian
William Hooper North Carolina Episcopalian
Robert Morris Pennsylvania Episcopalian
John Morton Pennsylvania Episcopalian
Stephen Hopkins Rhode Island Episcopalian
Carter Braxton Virginia Episcopalian
Benjamin Harrison Virginia Episcopalian
Thomas Nelson Jr. Virginia Episcopalian
George Wythe Virginia Episcopalian
Thomas Jefferson Virginia Episcopalian (Deist)
Benjamin Franklin Pennsylvania Episcopalian (Deist)
Button Gwinnett Georgia Episcopalian; Congregationalist
James Wilson Pennsylvania Episcopalian; Presbyterian
Joseph Hewes North Carolina Quaker, Episcopalian
George Clymer Pennsylvania Quaker, Episcopalian
Thomas McKean Delaware Presbyterian
Matthew Thornton New Hampshire Presbyterian
Abraham Clark New Jersey Presbyterian
John Hart New Jersey Presbyterian
Richard Stockton New Jersey Presbyterian
John Witherspoon New Jersey Presbyterian
William Floyd New York Presbyterian
Philip Livingston New York Presbyterian
James Smith Pennsylvania Presbyterian
George Taylor Pennsylvania Presbyterian
Benjamin Rush Pennsylvania Presbyterian