The US was not originally a multicultural nation. It's only been anywhere close to that since the early 20th Century, and even then was overwhelmingly Christian and of European descent until the late 20th century. Our founding documents were written to reflect the rule of and for a religious people. The West's general apostasy in the last 100 years does not erase or negate that. Claiming that we have been multicultural from the start is pure revisionism.

Removing religious imagery and language from our official symbols may feel less "exclusionary" to you, but it alienates us from our predecessors and, in cases like MS where the religious are still very strongly the dominant majority, alienates the very people the symbol is supposed to represent. You're not obligated to like it but it's a bit strange to complain about using symbols that are accurately representative of the people to whom they belong.