On January 1, 1802, President Thomas Jefferson wrote a letter to the Baptists of Danbury, Connecticut, who had requested clarification about the meaning of the First Amendment to the Constitution. Jefferson described the Establishment Clause of First Amendment by writing, "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 prohibit the free exercise thereof, thus building a wall of separation between church and state."
A wall of separation between church and state. This is a very strong statement, very clear in meaning. First of all, it means that the government cannot make laws that favor one religion over any other, because it cannot make laws related to the establishment of a religion or the free expression of religious beliefs. Therefore, individuals can pray in school, but public schools cannot require people to pray. The government cannot endorse any particular religion -- meaning there can be no copies of the Ten Commandments in front of schools, nor nativity scenes in government buildings, nor Buddha statues in front of government offices.
Religious leaders and their followers should relish in this wall of separation, rather than trying to knock it down. Why? Because it is there not only to keep religion out of government, but to keep government out of religion. The wall of separation goes both ways; the Establishment Clause protects not only the government from meddling by religious organizations, but protects religious organizations from interference with the practice of their beliefs by government as long as those beliefs do not require actions, like human sacrifice, that break laws not related to religious practice.
Clearly from the perspective of Jefferson, as was the case with many of his peers, the fledgling U.S. was not intended to be a country with any particular religion -- and certainly not a Christian country. The objective was to create an environment in which people were free to believe what they want without the government getting in the way; the best way to do that is to keep church and state apart.
Jefferson was committed to this separation because he had little faith in the capacity of a government run or even influenced by religious leaders to protect individual rights and ensure liberty for all. In a letter to Horatio Spafford in March of 1814, Jefferson wrote, "In every country and in every age, the priest has been hostile to liberty. He is always in alliance with the despot, abetting his abuses in return for protection to his own."
Nothing has changed as far as the truth of Jefferson's sentiments and the need to preserve the wall of separation between church and state as of 2016. Religious symbols, icons and phrases -- not just Christian, but any religion -- should be kept out of government buildings and organized prayer should be kept out of schools. This protects our freedoms, including the freedom of those who believe in ideas presented in documents like the Ten Commandments or the Lotus Sutra.
Those on the Christian right who would break down this wall of separation are doing a disservice to themselves, because the loss of the separation between church and state weakens the capacity of the government to protect the rights of anyone to practice their religious beliefs freely. Of course, it is possible that many on the Christian right do not believe in freedom of religion and instead want America to be a Christian nation (by which they mean their particular brand of Christianity) that is intolerant of the beliefs of others, whether Buddhist, Jewish, Unitarian Universalist, atheist or anything else.
If that is the case, then they do not support freedom of religion and, thus, do not support the Constitution and the principles upon which the United States was founded. That is their right as citizens of a free country. And the First Amendment, including the Establishment Clause, is the basis upon which that right is protected by the government. Such protection is the primary job of the government in a free society; it is not to support any particular religion.
Members of the Christian right should be among the strongest supporters of the Establishment Clause, because it allows them to believe what they want, even if what they want is anathema to freedom of religion.