There is only so much diversity a nation can handle before it starts to dissolve. The United States was formed as a nation that did not have a “state” religion as was the case in England. But not a single founding member of this country had any notion in the 18th century that one day America would be flooded with immigrants who were not Christians. In the past, we were a place of at the very least, nominal or cultural Christians and the freedom to worship was really about denominations within Christianity and not other foreign religions. It is an elementary principle in the definition of a culture or civilization to have shared elements one of which is religion. You cannot have a civilization of disaparate religiosity. It will fracture the culture as is happening now.
You could have stopped there. Everything else is superfluous.
When you flood an area with outsiders you change because they are the moving force.
When you allow outsiders in a few at a time and disperse them so they can not form enclaves that include the failed customs and culture that forced them to move you change them. Some of their culture and customs survives but only the harmless and superficial parts.
We have to stop with this mass immigration thing. Preferably forever but at least for 50 years.