I agree that the US was specifically not a Christian nation, but the basic concept of natural rights and the right of people to determine their government, which underpin our whole government, came out of (liberal) Christian political theory. Of course it can be traced to the Greeks, but the form in which it was used in the US does have a Christian background.
The United States of America was founded on massive land theft, hundreds of violated treaties with the tribal nations, white supremacy, and racism and discrimination against minorities. There were forced Indian removals, brutal massacres of Native Americans, 89 years of slavery, the Three-Fifths Compromise, and nearly two centuries of denying minorities civil rights and equality to white people.
Article VI of the United States Constitution states: "and all treaties made, or which shall be made, under the authority of the United States, shall be the
supreme law of the land" and yet the federal government violated every single legal treaty it signed with the tribal nations. Native Americans were either forcibly removed from their land or they were mercilessly slaughtered for their land.
For 148 years, Native Americans were denied citizenship until the American Indian Citizenship Act in 1924. They were also denied religious freedom for 202 years until the American Indian Religious Freedom Act in 1978. Until that law was passed, Native American religious dances were illegal and punishable by imprisonment. For 214 years, the religious sacred sites and burial grounds of Native Americans could be desecrated and tribal artifacts could be taken from those sacred sites without the permission from the tribe until the Native American Graves Protection and Repatriation Act in 1990.
For 89 years in the United States, slavery was legal and black people were believed to be inferior to white people. They were enslaved, beaten and killed because of the color of their skin.
For 99 years after slavery was abolished, the descendants of the freed slaves were systematically denied civil rights and equality to white people and they were legally segregated from white people until the Civil Rights Movement in 1964. They were denied the right to vote (despite the Thirteenth Amendment) until the Jim Crow Laws were abolished by the Voting Rights Act in 1965.
In America, black people were lynched and hung from trees. They had to sit at the back of the bus and were legally required to give up their seat to a white person. They were not allowed to eat at the same counter as white people in a public restaurant or use the same public restroom as white people or use the same drinking fountain as white people. Black children were not allowed to go to school with white children until its highest court intervened to put an end to segregation in public schools, but it took three years after the landmark Brown v. Board of Education case in 1954 before black children were finally allowed to attend public schools with white children. No more Separate but Equal.
In America, "No Colored" signs, "No Mexicans" signs, "No Indians and dogs" signs, and "Whites Only" signs once dawned public stores and restaurants. And despite all of these undeniable historical facts of America's real history, there has been a popular perpetual facade that the United States of America was originally founded upon freedom, liberty and justice for all. In fact, there are a multitude of
civil rights groups and
social justice groups to fight against discrimination that still exist in this country.