“In God we trust” was first added to U.S. coins in 1864, during the Civil War. The motto was adopted by the U.S. Congress as the national motto in 1956, during the Cold War.

There are a few reasons why the motto was added to U.S. currency. One reason is that it was seen as a way to unify the country during the Civil War. The motto was also seen as a way to distinguish the United States from its communist rivals.

The motto “In God we trust” has been challenged several times because it violates the First Amendment’s Establishment Clause, which prohibits the government from establishing a state religion. However, the Supreme Court has upheld the use of the motto on currency, ruling that it does not violate the Establishment Clause because it is a secular motto not associated with any particular religion.