Thomas Jefferson: 

“Believing with you that religion is a matter which lies solely between man and his God, that he owes to none other for his faith or his worship, that the legislative powers of government reach actions only, and not opinions, 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.” (emphasis ours)

James Madison, 1789-JUN-7 “The Civil Rights of none shall be abridged on account of religious belief or worship, nor shall any national religion be established, nor shall the full and equal rights of conscience be in any manner, nor on any pretext infringed. No state shall violate the equal rights of conscience or the freedom of the press, or the trial by jury in criminal cases.”

” In the spring of 1778, the Constitutional Convention was held in Philadelphia, PA. They resolved three main religious controversies. They:

	Decided that there would be no religious test, oath or other requirement for any federal elected office
	Allowed Quakers and others to affirm (rather than swear) their oaths of office
	Refrained from recognizing the religion of Christianity, or one of its denominations, as an established, state church.

More here.

With all the excessive interest shown in Mitt Romney’s religion, it might be worth noting that the founders were expressly prohibiting tests/oaths of faith for office, protecting freedom of religion, as well as endorsing freedom from (an established, or state) religion.

The main problem underlying church state doctrine is that constitutional law has never gone into what constitutes a religion (hence most of the seminal cases are filled with ambiguity and either favor the state or majority religion too heavily (Scalia’s opinions) or are simply confused (O’Connor). In my opinion, a number of cultural Marxist positions that are now promoted as universal and imposed as such do violate church- state separation if we read the word church broadly to include orgnaized beliefs that go to the “fundamentals” of life (nature of human life, gender roles and family, existence of the soul and afterlife, or not).

So, on a matter such as abortion, where there are several credible moral and theological positions possible, devolution to the states is the best guarantor that diversity of opinion will really be preserved.