DENVER—Five Air Force Academy faculty members and a religious watchdog group asked a federal judge on Monday to block the school from sponsoring a National Prayer Luncheon event.

The Military Religious Freedom Foundation and the faculty members filed a lawsuit in Denver federal court, saying the event appears to be sponsored and approved by the academy’s command structure. The suit says that violates the constitutional requirement for separation of church and state.

Academy spokesman Lt. Col. John Bryan said the event is voluntary and that officials are aware of the lawsuit.

“We will let the legal process take its course and will certainly abide by the ruling issued from the court,” he said in a written release.

The lawsuit seeks a preliminary injunction to stop the Feb. 10 event, which is a lunch with retired Marine Lt. Clebe McClary as the speaker. Cadets, faculty and others at the school received invitations to attend.

McClary’s website describes him as a motivational and inspirational speaker. It says that for him, the Marine Corps abbreviation “USMC” means “U.S. Marine for Christ,” and that now he is “in the service of the Lord’s Army.”

McClary said Monday he didn’t understand the objections to the event. He said no one is required to attend.

“I lost an arm and eye in Vietnam and was wounded seven times,” he told The Associated Press. “If you aren’t fighting for (freedom of speech and freedom of religion), what’s happening to freedom in this country?”

David Lane, the Denver attorney representing plaintiffs, said the lawsuit is not anti-religion.

He said any club or organization could use school facilities for an event with a religious speaker, as long as other organizations are given the same opportunity. But in this case, the school itself and its command structure appear to be endorsing and promoting the event using government e-mail and the academy insignia, Lane said.

“The government is not allowed to embrace or elevate any religion,” Lane said in an interview. “This is the command structure of the Air Force Academy sponsoring and endorsing religion. That is a violation of the First Amendment.”

The lawsuit says the fact that McClary’s book will be sold by the academy’s base exchange, rather than the chapel, contributes to the appearance that the academy is promoting the event.

The suit acknowledges that the event is being paid for by the academy’s chapel tithes and offerings fund, not taxpayer money.

The suit says attendance is officially voluntary but that the five faculty members and unspecified other people at the academy believe their careers might suffer if they don’t go.

Only one of the five faculty members listed as plaintiffs is identified, R. David Mullin, an assistant professor of economics. He didn’t immediately return calls seeking comment.

The lawsuit says the other four aren’t identified by name because they fear retribution. They are listed as John Doe No. 1 through No. 4.

Mikey Weinstein, president and founder of the Military Religious Freedom Foundation, called the event “a clear and obvious violation of the separation of church and state.”