The phrase, “separation of church and state”, was used by Thomas Jefferson when he said,
“Believing with you that religion is a matter which lies solely between Man & his God, that he owes account to none other for his faith or his worship, that the legitimate powers of government reach actions only, & 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…"
Here it is clear that the “separation of church and state” phrase, sometimes referred to as the “wall” phrase, was used by Jefferson to explain that the government should not establish a state religion as had England. Jefferson also stated that the government should not prohibit the American people from exercising their religious beliefs. This includes those who serve in government positions.