Christianity and the First Amendment
The United States of America were established as a Christian federalist republic made up of Christian States. There was no established church in our federal Republic of states and any attempt to establish a church on the federal level would have destroyed the chance for the Constitution to be ratified.
The states that ratified the Constitution were all “Christian” states (i.e. nations), most of them overtly so. Some of them had established churches, some had recently disestablished their official churches and some had never had official “state” churches but all were still Christian republics.
At least four of the original states that ratified the Constitution and the Bill of Rights had established churches when they voted to approve the Constitution and the 1st Amendment to the Constitution, which contains the "establishment Clause."
No one saw this as odd or in conflict with either the Constitution or the First Amendment to the Constitution. Even those states that had recently disestablished their official churches still saw themselves as Christian. North Carolina is a good example of this.
In 1776 North Carolina (then a state and no longer a colony of Great Britain) adopted a new state Constitution, which remained in use until after the War Between the States. Prior to 1776 the Anglican Church was the official church of North Carolina. The Anglican establishment ended with the Constitution of 1776, but North Carolina remained Christian.
Here are some excerpts from her Constitution:
XXXII. That no person, who shall deny the being of God or the truth of the Protestant religion, or the divine authority either of the Old or New Testaments, or who shall hold religious principles incompatible with the freedom and safety of the State, shall be capable of holding any office or place of trust or profit in the civil department within this State. (Note: In 1835 the term Protestant was broadened to the word Christian.)
XXXIV. That there shall be no establishment of any one religious church or denomination in this State, in preference to any other; neither shall any person, on any pretence whatsoever, be compelled to attend any place of worship contrary to his own faith or judgment, nor be obliged to pay, for the purchase of any glebe, or the building of any house of worship, or for the maintenance of any minister or ministry, contrary, to what he believes right, or has voluntarily and personally engaged to perform; but all persons shall be at liberty to exercise their own mode of worship:-- Provided, That nothing herein contained shall be construed to exempt preachers of treasonable or seditious discourses, from legal trial and punishment.
North Carolina’s constitution was clearly Christian and no one called into question that this was unconstitutional.
New Hampshire disestablished the Congregational Church a few years after she ratifed the Constitution. This was voluntary on her part and even with the disestablishment the state constitution remained overtly Christian.
Here is a section from the 1784 New Hampshire Constitution:
VI. As morality and piety, rightly grounded on evangelical principles, will give the best and greatest security to government, and will lay in the hearts of men the strongest obligations to due subjection; and as the knowledge of these, is most likely to be propagated through a society by the institution of the public worship of the DEITY, and of public instruction in morality and religion; therefore, to promote those important purposes, the people of this state have a right to impower, and do hereby fully impower the legislature to authorize from time to time, the several towns, parishes, bodies-corporate, or religious societies within this state, to make adequate provision at their own expence, for the support and maintenance of public protestant teachers of piety, religion and morality…
… And every denomination of christians demeaning themselves quietly, and as good subjects of the state, shall be equally under the protection of the law: and no subordination of any one sect or denomination to another, shall ever be established by law.
The New Hampshire constitution remained valid, even after the state ratified the U.S. Constitution, and again no one saw any contradiction between the N.H. Constitution and the U.S. Constitution. New Hampshire did not allow non-Protestants to hold office until she changed that provision (on her own) in the 1870’s.
Now let's move on to an early commentary on the U. S. Constitution. Supreme Court Justice Joseph Story (Justice from 1811-1845) is one of the giants of the Supreme Court. In his 1833 Commentaries on the Constitution he writes a good bit on the Establishment Clause of the First Amendment. Every American should be read all that he wrote on this important clause, but let me quote one part. Justice Story said “The real object of the amendment was, not to countenance, much less to advance Mahometanism, or Judaism, or infidelity, by prostrating Christianity; but to exclude all rivalry among Christian sects, and to prevent any national ecclesiastical establishment, which should give to an hierarchy the exclusive patronage of the national government. It thus cut off the means of religious persecution, (the vice and pest of former ages,) and of the subversion of the rights of conscience in matters of religion, which had been trampled upon almost from the days of the Apostles to the present age.”
That is one of the most succinct and accurate statements on the amendment that has ever been made.