I've seen a number of incidents...most notably the Texas Republican Party, who in their recent convention declared America a "Christian nation". Also, that is the unstated (but obvious) purpose of the posting of articles like this.
"A "state religion" is what the establishment clause is all about. The founders wanted no part of a Church of the United States."
Completely agree. However, there ARE some out there who want to push the idea.
Such a declaration is in no way a violation of the First Amendment. Also, in no way was the Texas Republican Party advocating a Church of the USA or any other "state religion."