I'd like to shed a little light on the misunderstood concept of Separation of Church and State and its origins. President Thomas Jefferson replied to a group of Baptists in Danbury, Connecticut who wrote to him because they were concerned about the possible establishment of a church that they would be required to attend. Jefferson wrote to ensure them that their free practice of religious liberty would never be interfered with by the government, for that would go against the will of the people and the Constitution. Keep in mind that our founders left a country where membership in a national church was mandatory, Jefferson closed his letter by thanking them for their prayers on his behalf.
"Believing with you that religion is a matter which lies solely between Man and his God, that he owes account to none other for his faith or his worship, that the legitimate powers of government reach actions only and not opinions, 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. Adhering to this expression of the supreme will of the nation in behalf of the rights of conscience, I shall see with sincere satisfaction the progress of those sentiments which tend to restore to man all his natural rights, convinced he has no natural right in opposition to his social duties.
I reciprocate your kind prayers for the protection and blessing of the common father and creator of man, and tender you for yourselves and your religious association, assurances of my high respect and esteem."
Thomas Jefferson, Jan. 1, 1802.
From what I understand, it is the only document that exists addressing this question. I can't help but wonder if this is taught in history class in schools.