Wow, indeed.
Here are two links, regarding the specific origin of "In God We Trust" on U.S. currency:
This first one, from the U.S. Mint website, tracing the origin of "In God We Trust", first authorized for U.S. coins
in 1866, and then later to paper currency in 1957.
HERE
And this second site, which focuses specifically on the introduction of "In God We Trust" to U.S. paper currency:
http://asms.k12.ar.us/armem/martin/
You will notice that Senator McCarthy was not mentioned in either of these articles.
McCarthy's hand in these events must have been enormous.
