PHILADELPHIA, Jan. 13 (UPI) -- In what has become a ritual before U.S. presidential inaugurations, a group of atheists has sued seeking to keep references to God out of the ceremony.

"Our Founding Fathers knew that to put an oath to God would be hypocritical to the entire secular Constitution," Margaret Downey, founder of the Freethought Society of Greater Philadelphia and one of the plaintiffs, told the Philadelphia Inquirer.


Michael Newdow, who waged a legal battle to remove the words "under God" from the Pledge of Allegiance, filed similar lawsuits before the previous two inaugurations, only to have them dismissed. This time, he is joined by more than 20 atheists and agnostics across the country who have asked a judge to keep God references out of the inaugural oath and to bar the Rev. Rick Warren from giving an invocation.

A hearing is set for Thursday in Philadelphia.

The oath of office as given in the Constitution does not include the words "So help me God," and Beth Hahn of the U.S. Senate Historical Office said its first known use was in 1881 when Vice President Chester Arthur was sworn in to succeed the assassinated James Garfield. Having a minister deliver a prayer is even more recent, dating from Franklin Roosevelt's second inaugural in 1937.