Origin
“In God we trust” is the official motto of the United States of America. It was adopted by Act of Congress on July 30, 1956 (Public Law 84-140), signed by President Eisenhower. The previous year, in 1955, Congress had made the inscription mandatory on all US currency.
The phrase first appeared on US coinage in 1864 — a two-cent piece minted during the American Civil War. The inscription was proposed by Secretary of the Treasury Salmon P. Chase, who responded to a wartime push for explicit recognition of God on US currency. From 1864 it appeared intermittently on US coins, and in 1957 began appearing on paper currency.
The 1956 adoption as the national motto was, by historical context, partly a Cold War move — distinguishing the United States from the officially atheist Soviet Union. The phrase replaced E pluribus unum (from many, one) as the official motto, though both remain in use.
Possible literary source
The phrase echoes the last stanza of Francis Scott Key’s “The Star-Spangled Banner” (1814), which contains the line And this be our motto: In God is our trust. Key’s stanza draws loosely on Psalm-style trust language but contains no direct citation of a specific biblical verse.
What the Bible says about trust
The biblical vocabulary of trust is rich. Hebrew batach (בָּטַח) — see [/word/ entries on trust language] — is the concrete physical verb for resting one’s weight on a support. It is used dozens of times in the Hebrew Bible for trust placed in God, in human allies, in chariots, in horses, in wealth, in princes. Greek pisteuō (πιστεύω) in the New Testament carries similar weight.
The closest biblical passage to the US motto is Psalm 20:7: Some trust in chariots and others in horses, but we trust in the name of the LORD our God. The verse contrasts trust in military technology with trust in the divine name. It is not identical to the motto but expresses a related sentiment.
The phrase “In God we trust” itself is American civic vocabulary, not biblical citation.