A group of atheists and agnostics filed a federal lawsuit Wednesday seeking to stop an evangelical Christian prayer event next month that was proposed and is endorsed by Texas’ governor.

The Freedom from Religion Foundation argues in its lawsuit filed in Houston that Republican Gov. Rick Perry’s day of prayer and fasting would violate the constitutional ban on the government endorsing a religion. The event, which is called “The Response” and is billed as Christian-only, is scheduled for Aug. 6 at Houston’s Reliant Stadium.

“The plaintiffs seek a declaration that Texas Governor Rick Perry’s initiation, organization, promotion and participation as governor in a prayer rally at Reliant Stadium … violates the Establishment Clause of the First Amendment to the United States Constitution,” the complaint says.

Perry’s spokeswoman, Catherine Frazier, said the lawsuit will not change the Governor’s plans.

“He believes it will serve as an important opportunity for Americans to gather together and pray to God, seeking his wisdom and guidance as our nation navigates the challenges before it. The pending litigation does not affect plans for the prayer event to carry out as planned.” Frazier said.

Perry invited the Obama administration, the nation’s governors and Texas lawmakers to attend the event.

“Given the trials that beset our nation and world, from the global economic downturn to natural disasters, the lingering danger of terrorism and continued debasement of our culture, I believe it is time to convene the leaders from each of our United States in a day of prayer and fasting, like that described in the book of Joel,” Perry said in his open invitation to attend the event on June 3.

The event is being sponsored by several evangelical Christian groups, including the American Family Association, which has been criticized by civil rights groups for promoting anti-homosexual and anti-Islamic positions on the roughly 200 radio stations it operates.

The Freedom from Religion Foundation said it does not oppose politicians taking part in religious services, but that Perry crossed a line by initiating the event, using his position as governor to endorse and promote it and by using his official website to link to the organizer’s website. The plaintiffs also contend that Perry’s use of Texas’ official state seal to endorse the event and his plans to issue an official proclamation violate the Constitution.

“The answers for America’s problems won’t be found on our knees or in heaven, but by using our brains, our reason and in compassionate action,” said Dan Barker, a co-director of the foundation. “Gov. Perry’s distasteful use of his civil office to plan and dictate a religious course of action to ‘all citizens’ is deeply offensive to many citizens, as well as to our secular form of government.”