Original United States pledge of allegiance (c. 1892), 44 star flag (Wyoming, c. 1890).

The words, "under God" were added at the height of McCarthyism and the Cold War. Because communists don't believe in God. It is not necessary.

That is not accurate. There were, in fact, Communist Christians. (Though even the likes of MLK Jr. suggested that such a thing was "diametrically opposed".)

That would simply be yet another reason to point out that religion is bullshit.