Before one decides the USA was founded as a Christian nation, it might be worthwhile to do some research on the religious belief of Thomas Jefferson.
It would also be worthwhile to do some research on the long history of perpetual racism and discrimination against minorities before deciding the USA was founded as a Christian nation.
For example...
The United States is a nation that was originally founded on massive land theft, hundreds of violated treaties, white supremacy, and the subjugation and discrimination against minorities. It is a nation built on perpetuated lies and stolen tribal lands. Black people, Native Americans and other minorities did not have the same freedom or liberties or justice that White Anglo-Saxon Protestant people had when this country was originally founded. It took this country 188 years and a Civil Rights Movement to finally live up to its claims of freedom, liberty and justice for all and give those rights to minorities.
The United States is a nation where black people were being lynched and hung from trees. It is a nation where black people had to sit at the back of the bus and were legally required to give up their seat to a white person. It is a nation where black people couldn't 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. It is nation where black children were not allowed to go to school with white children until its highest court intervened and ended legal segregation in public schools.
The United States is a nation where black people and other minorities were denied suffrage until a year after the Civil Rights Act was passed in 1964. It is a nation where "No Colored" signs, "No Mexicans" signs, "No Indians and dogs" signs, and "Whites Only" signs dawned public stores and restaurants while the Jim Crow Laws were still in effect before the Voting Rights Act in 1965 put an end to those racist laws. The United States of America is a nation that was born in genocide.
“The original sin of this country is that we invaders shot and murdered our way across the land killing every Native American we could, and making treaties with the rest. This country was founded on genocide before the word genocide was invented, before there was a war crimes tribunal in The Hague.” Source:
This Nation Was Founded on Genocide: MSNBC’s Lawrence O’Donnell
"Our nation was born in genocide when it embraced the doctrine that the original American, the Indian, was an inferior race. Even before there were large numbers of Negroes on our shores, the scar of racial hatred had already disfigured colonial society. From the sixteenth century forward, blood flowed in battles of racial supremacy. We are perhaps the only nation which tried as a matter of national policy to wipe out its Indigenous population. Moreover, we elevated that tragic experience into a noble crusade. Indeed, even today we have not permitted ourselves to reject or feel remorse for this shameful episode. Our literature, our films, our drama, our folklore all exalt it." Martin Luther King, Jr. Source:
Dr. King spoke out against the genocide of Native Americans