The atheist known for trying to remove the phrase "one nation under God" from the Pledge of Allegiance also wants to ban references to God during the Presidential inauguration.

Michael Newdow filed a lawsuit this week to have "so help me God" removed from the oath of office.

He believes the phrase and invocation prayer to be given by Pastor Rick Warren are unconstitutional.

Peter Sprigg of the Family Research Council disagrees.

"Having a simple prayer at an inaugural ceremony doesn't come anywhere close to" violating the establishment clause in the First Amendment, he told Fox News.

"If a lawsuit like this were to succeed, we would in effect be establishing atheism as the national religion," Sprigg added.

Newdow sued to remove references to God from inaugurations in 2001 and 2005, but lost both cases.