@daverod,
Many U.S citizens (?) claim that the U.S was not founded upon Christianity or upon Christian morals or even Holy Biblical principles. This 'theory' or 'piece of 'history'' has been shown and can be proven as not true.
And as far as the Establishment Clause is concerned, the separation of Church and State:
"The First Amendment has two provisions concerning religion: the Establishment Clause and the Free Exercise Clause.
The Establishment clause prohibits the government from "establishing" a religion. The precise definition of "establishment" is unclear.
Historically, it meant prohibiting state-sponsored churches, such as the Church of England."
http://www.uscourts.gov/educational-resources/educational-activities/first-amendment-and-religion
But England, France, Germany, Italy and many other 'Countries' had, at least, a State Religion which was sponsored by the Government. And some Countries still do have State Religions where The State 'sponsors' a certain 'faith/religion'.
Governments which recognize
Buddhism as their official religion:
Bhutan (Drukpa Kagyu school of Tibetan Buddhism)
Cambodia (Theravada Buddhism)
Kalmykia, a republic within the Russian Federation (Tibetan Buddhism - sole Buddhist entity in Europe)[1]
Thailand (Theravada Buddhism)
Tibet Government in Exile (Gelugpa school of Tibetan Buddhism)
Myanmar- written in the 1974 constitution
Sri Lanka
Presbyterian:
Scotland (Church of Scotland) established by law
Scotland assorted Free Presbyterian churches, unestablished.
Lutheran:
Denmark (Church of Denmark)
Iceland (Church of Iceland)
Norway (Church of Norway)
Finland (Evangelical Lutheran Church of Finland)
Anglican:
England (Church of England) established by law; plus, unestablished, the world-wide Anglican Communion
States without any state religion
These states do not profess any state religion. Countries which officially decline to establish any religion include:
Australia
Azerbaijan
Canada
Chile
People's Republic of China (China)
Colombia
Czech Republic
East Timor
France
India
Ireland
Japan
Nepal
Netherlands
New Zealand
Nigeria
Philippines
Portugal
Republic of China (Taiwan)
Romania
Singapore
South Africa
South Korea
Switzerland
Turkey
United States of America
Colony : Denomination: Disestablished
Connecticut: Congregational: 1818
Georgia: Church of England: 1789
Massachusetts: Congregational: 1780
New Brunswick: Church of England
New Hampshire: Congregational: 1790
Newfoundland: Church of England
North Carolina: Church of England: 1776
Nova Scotia: Church of England: 1850
Prince Edward Island: Church of England
South Carolina: Church of England: 1790
Upper Canada: Church of England: 1854
West Florida: Church of England : N/A
East Florida: Church of England: N/A
Virginia: Church of England: 1786
West Indies: Church of England: 1868
https://simple.wikipedia.org/wiki/State_religion