From 1775 through 1781, the Second Continental Congress functioned as our de facto national government without a Constitution. In 1781, the first Constitution of the United States of America, the Articles of Confederation and Perpetual Union, were ratified. From 1781-1789 the Congress of the Confederation operated as our national government.
In 1788, the Articles of Confederation were superseded by the ratification of a new United States Constitution. Significantly, this Constitution did not establish religion, something no government had ever done in the past.
In 1791, the Bill of Rights was adopted as the first 10 Amendments to the Constitution (The First Amendment reads in part: “Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof…”).
In 1797 the Treaty of Tripoli was ratified (Article 11 of the Treaty reads in part: “…the Government of the United States of America is not, in any sense, founded on the Christian religion…”). Article VI, Sect.2 of the Constitution states that “all treaties made, or which shall be made, under the authority of the United States, shall be the supreme law of the land.” The Treaty was ratified unanimously and the full text was published in The Philadelphia Gazette on June 17th, 1797, without any record of any public dissent.
In 1868, the Fourteenth Amendment was adopted. It made the Bill of Rights applicable to the states.
For more information:
The U.S. Constitution – transcript
The Bill of Rights – transcript
Treaty of Tripoli – transcript (see Article 11)
Little-Known U.S. Document Signed by President Adams Proclaims America’s Government Is Secular