WASHINGTON  The nation's largest group of atheists and agnostics filed a federal lawsuit Tuesday to stop the engraving of "In God We Trust" and the "one nation under God" from the Pledge of Allegiance in the new Capitol Visitor Center.

The Freedom From Religion Foundation, a Wisconsin-based church-state watchdog group, claimed the engravings are unconstitutional and would exclude the 15% of Americans who identify themselves as non-religious.

"We are effectively being told that we are political outsiders ... because we don't trust in God," said Annie Laurie Gaylor, co-president of the Freedom From Religion Foundation.

The House and Senate passed resolutions this month approving the inscription of the mottos in prominent areas of Capitol Visitor Center, which serves as the entrance and security screening for tourists.

Sen. Jim DeMint, R-S.C., who sponsored the bill in the Senate, said historical references to God should not be censored for political correctness.

"The Founders based the Constitution and our laws on religious faith and principles that clear the way for individual freedom," he said in a statement. "Our true motto, 'In God We Trust,' expresses this fact, and we cannot allow a whitewash of America's religious heritage."

However, Gaylor said the mottos are inaccurate since "In God We Trust" and the insertion of "under God" into the Pledge of Allegiance were adopted in the 1950s as anti-communist measures.

"They wanted this up there because they think God is the foundation of our government," Gaylor said. "Boy, are they misinformed."

Rep. Louie Gohmert, R-Texas, reminded colleagues Tuesday that the Washington Monument displays the words "Praise be to God" in Latin on the side that faces the Capitol. He said "every day when the first rays of God's sun hit the very first thing in this Nation's Capitol," those words are illuminated.

Rep. Steve King, R-Iowa, added in a statement, "Our Judeo-Christian heritage is an essential foundation stone of our great nation."

In a separate suit, Gaylor's foundation is also suing defendants President Obama, White House Press Secretary Robert Gibbs and Shirley Dobson of the National Day of Prayer Taskforce for proclaiming the National Day of Prayer in May. Gaylor said the proclamations violate the separation of church and state. U.S. District Judge Barbara Crabb of Wisconsin has denied motions by the Obama administration to dismiss the case.