Robert N. Bellah has in his writings that although the separation of church and state is grounded firmly in the constitution of the United States, this does not mean that there is no religious dimension in the political society of the United States. He used the term "Civil Religion" to describe the specific relation between politics and religion in the United States. His 1967 article analyzes the inaugural speech of John F. Kennedy: "Considering the separation of church and state, how is a president justified in using the word 'God' at all? The answer is that the separation of church and state has not denied the political realm a religious dimension."

What does Bellah say the separation of church and state is grounded firmly in?