Protests by conservative lawmakers led architects to promise to add "In God We Trust" as the national motto and to engrave the Pledge of Allegiance in the new $621 million Capitol Visitor Center.
Sen. Jim DeMint, a South Carolina Republican, had threatened to delay Tuesday's opening of the marble-and-stone center that took seven years to build at triple the original cost.
The estimated 3 million people who tour the U.S. Capitol each year will now assemble in a grand monument-like building likely to become a tourist stop on its own.
After taking a tour of the visitor center in September with Steven Ayers, the architect of the Capitol who oversaw its completion, DeMint correctly noted that it had erroneously described "E. Pluribus Unum" - Latin for "from many, one" - as the national motto rather than "In God We Trust."
"The current Capitol Visitor Center displays are left-leaning and in some cases distort our true history," DeMint said. The center's "most prominent display proclaims faith not in God, but in government."
Despite winning a months-long battle to highlight the importance of religion in American life, DeMint said the center still misrepresents American history by downplaying the faith of the founding fathers and other prominent figures.