On July 30, 1956, two years after pushing to have the phrase
“under God” inserted into the Pledge of Allegiance, President
Dwight D. Eisenhower signed a law officially declaring “In God
We Trust” to be the nation’s official motto. The law, P.L. 84-140,
also mandated that the phrase be printed on all American
paper currency.

The phrase had been placed on U.S. coins since the Civil War
when, according to the historical association of the United
States Treasury, religious sentiment reached a peak.

Dwight David "Ike" Eisenhower
(October 14, 1890 – March 28, 1969)

According to History. com, on this day in history, July 30,
1956, the 84th Congress passed a joint resolution declaring
"IN GOD WE TRUST" to be the national motto of the United
States.

The same source noted. passing in both the House and the
Senate unanimously and without debate, the resolution
replaced "E pluribus Unum," which had existed before as
a de facto official motto.