Thomas Jefferson interpreted the 1st Amendment in his famous letter to the Danbury Baptist Association in January 1, 1802:
"I contemplate with sovereign 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."
Some Religious activists try to extricate the concept of separation between church and State by claiming that those words do not occur in the Constitution. Indeed they do not, but neither does it exactly say "freedom of religion," yet the First Amendment implies both.
As Thomas Jefferson wrote in his Autobiography, in reference to the Virginia Act for Religious Freedom:
"Where the preamble declares, that coercion is a departure from the plan of the holy author of our religion, an amendment was proposed by inserting "Jesus Christ," so that it would read "A departure from the plan of Jesus Christ, the holy author of our religion;" the insertion was rejected by the great majority, in proof that they meant to comprehend, within the mantle of its protection, the Jew and the Gentile, the Christian and Mohammedan, the Hindoo and Infidel of every denomination."
James Madison, perhaps the greatest supporter for separation of church and State, and whom many refer to as the father of the Constitution, also held similar views which he expressed in his letter to Edward Livingston, 10 July 1822:
"And I have no doubt that every new example will succeed, as every past one has done, in shewing that religion & Govt will both exist in greater purity, the less they are mixed together."