In 1779, Thomas Jefferson was concerned about the power of the Church of England (Romish) within Virginia. He felt a guarantee of religious freedom was the best guarantee that America would avoid the religious intolerance and religiously inspired bloodshed that had marked much of the history of Europe. He wrote an Act for Establishing Religious Freedom; after a long battle, it became law in Virginia on 1786-JAN-16. The First Amendment of the U.S. Constitution was based in part on that act.
Thomas Jefferson, as president, wrote a letter to the Danbury Baptist Association of Connecticut on 1802-JAN-1. It contains the first known reference to the "wall of separation". The essay states in part:
"...I contemplate with solemn reverence that act of the whole American people which declared that their legislature should 'make no law respecting an establishment of religion, or prohibiting the free exercise thereof,' thus building a wall of separation between Church and State..."
During the 1810's, President James Madison wrote an essay titled "Monopolies" which also refers to the importance of church-state separation. He stated in part:
"Strongly guarded as is the separation between religion and Government in the Constitution of the United States, the danger of encroachment by Ecclesiastical Bodies may be illustrated by precedents already furnished in their short history."
The US Supreme Court has interpreted the First Amendment as if it requires this "wall of separation" between church and state. It not only prohibits any government from adopting a particular denomination or religion as official, but requires government to avoid excessive involvement in religion.
Were it not for the 1st Amendment rights we would all be suffering under the iron hand of Rome. Historically documented evidence proves this.