America is a Christian nation...so far
While the Constitution is neutral concerning religions, it is not neutral concerning religious philosophy. The official neutrality among religions is an impartiality among specific denominations. It is not, and never was, a proscription against religion itself, nor against Christianity in particular. On the contrary, the Constitution embodies and codifies Judeo-Christian values from beginning to end.
It is for this reason that in 1892, the United States Supreme Court declared (in Holy Trinity v. United States) that the historical record of America overwhelmingly demonstrates that the United States "is a Christian nation."
The first American document that undeniably demonstrates this is the Mayflower Compact. It specifically states that the founding of the new government is "for the glory of God, and advancement of the Christian faith."
Although our form of government owes much to the Greco-Roman tradition and its antecedents, those were mere formats. Their underpinnings, by themselves, did not survive the ages. The Hebrew and Christian laws provide the vital foundation, without which the structure of tripartite government is but an empty shell. Many Constitutions since 1788 have been tried and failed, making ours the oldest continuous one in the world, because it is founded not on shifting sand, but on the eternal rock of Truth.
Our Christian nation has survived many dangers and snares, yet it has one, possibly terminal, weakness. According to John Adams, the Constitution "was made only for a moral and religious people. It is wholly inadequate to the government of any other."
In other words, one cannot send a copy of the Constitution to a nation that does not share its cultural and religious roots and expect that nation to succeed. Our nation's spiritual character is its strength, but in modern times, we are seeing it weakening, perhaps fatally.
Forces are at work within our nation to destroy it. Those forces have enjoyed many victories. One recent indication of this is that, regarding a public park in Pensacola, Florida, a judge has ordered the removal of a Christian cross, despite a long history of such symbols being prominently displayed there.
The issue is much more important than the symbol. Much worse rulings have cut at the very fabric of our nation's morality. Abortion, redefining marriage, and the wholesale immigration of unassimilable aliens who are hostile to our values have corroded the nation in many ways. The full impact of those rulings is going unnoticed, and if not reversed, they will bring us ruin.
Politics will not remedy this. Only a spiritual revival will rescue us.