Marines...bow their heads as they pray during a traditional cake-cutting ceremony held in honor of the United States Marine Corps' 235th birthday at Camp Leatherneck, Afghanistan... By Cpl. Shannon E. McMillan

US Marine LtCol Matthew Palma, the commanding officer of 3rd Battalion, 3rd Marine Regiment...receives the prayer of a mullah...in honor of fallen District Chief of Police Lt. Col. Sayfullah Khan Rashidi during his funeral here. Photo by Cpl. Reece Lodder

Troops bow their heads during a chaplain's prayer at a ramp ceremony at Kandahar Airfield, Afghanistan. (Sgt. Ashleigh A. Bryant, Courtesy of USMC)

A US Air Force chaplain leads C-17 pilots and aircrew in prayer prior to takeoff for missions over Afghanistan during the opening stages of Operation Enduring Freedom. (USAF Photo by Mannie Garcia, Gannett, ATPCo)

Airmen and Soldiers take a moment to pray for each other's safety before heading out for another day of convoy duty in Iraq. (U.S. Air Force photo by Staff Sgt. Scott Campbell)

Caption in work.

Airmen group together for a prayer, a tradition, prior to every mission outside the wire in Iraq, November 2008. (U.S. Navy photo/Petty Officer 2nd Class Todd Frantom)

Air Force Chaplain (Capt.) Jeffrey Granger prays for the safety of a group of Soldiers about to embark on a convoy mission. (U.S. Air Force photo/ Senior Airman Julianne Showalter)

11/8/05 -- Soldiers gather together to pray moments before setting off on a patrol of western Baghdad.

David Furst / Agence France-Presse / Getty Images

Airmen at an Army camp in Southwest Asia bow their heads during a prayer before heading off on a convoy. (U.S. Air Force photo/Staff Sgt. Patrick Dixon)

Airmen, Soldiers and civilians pray before heading out on a convoy mission in Iraq. (U.S. Air Force photo by Master Sgt. Lance Cheung)

Airmen and Soldiers take a moment to pray for each other's safety before heading out for another day of convoy duty in Iraq. (U.S. Air Force photo by Staff Sgt. Scott Campbell)

Apr. 24, 2004 - Team members assigned to a Vessel Board Search and Seizure (VBSS) aboard the USS Whidbey Island's (LSD 41), huddle up as the ship's Chaplain says a prayer while deployed in support of Operation Iraqi Freedom. U.S. Navy photo by Photographer's Mate 1st Class Bart Bauer.

Operation Iraqi Freedom -- Pilot kneels in front of F-16 Fighting Falcons resting on the flight line. Illustration by Bryan Snuffer.

Army Times 2009 "Soldier of the Year" 1st Sgt. Peter J. Lara talks with Chief of Staff of the Army Gen. George W. Casey Jr. and Brig. Gen. Bradley May at Fort Jackson, S.C., on July 30, 2009.

Maj. Gen. Vincent Brooks pauses with Command Sgt. Maj. Jim Champagne at the stones of fallen Big Red One Soldiers during the Victory Park memorial ceremony. Photo Credit: Stroda/1st ID PAO.

BAGHDAD-Maj. Toby Clifton kneels in front of a memorial to the three brigade Soldiers killed by a bomb in Iraq.

Alabama Air National Guard Chaplain (Lt. Col.) Robert Hicks prays with two U.S. servicemembers. (U.S. Army photo by Master Sgt. Bob Haskell)

Firefighters pray during a one-minute "final alarm" ceremony honoring Staff Sgt. Ray Rangel who died while attempting to rescue two Soldiers after their Humvee overturned in a canal in Iraq. (Courtesy photo)

Chaplain (Maj.) Charles Perry prays with Senior Airman Josh Jacobs, Army 2nd Lt. Scott Nelles and Army Spc. Brian Collins. (Altered U.S. Air Force photo by Tech. Sgt. Melissa Phillips)

US Air Force LtCol Conrado Navarro, head chaplain, offers a prayer during the September 11th Remembrance Walk, held to remember those who lost their lives on September 11, 2001. (U.S. Air Force photo/Airman 1st Class Chad M. Kellum)

US Air Force Honor Guard Drill Team Airmen gather for a word of prayer before their performance at the Palo Verde High School gym in Las Vegas, Nev. (U.S. Air Force photo/Senior Airman Larry E. Reid Jr.)

Soldiers pray during a Memorial Day ceremony at Camp Victory in Baghdad on May 25, 2009. (Dusan Vranic, Associated Press)

Airmen take a moment to pray for the family of a fellow Airman who made the ultimate sacrifices during a street dedication ceremony in Southwest Asia. The ceremony is a tribute to Airman 1st Class Eric Barnes who died June 10, 2007, as a result of an improved explosive device attack on an Air Force convoy about 100 miles south of Baghdad, Iraq. (U.S. Air Force photo/Tech. Sgt. Michael O'Connor)

Feb. 16, 2003 -- Marines and Sailors listen to Chaplain (LtCmdr) Michael L. Greenwalt recite passages from the Bible during a prayer service while deployed in support of Operation Enduring Freedom. U.S. Marine Corps photo by Lance Cpl. Matthew J. Decker.

Chaplain prays with US Navy SEAL instructors.

More than 300 Airmen and Soldiers bow their heads in prayer during a memorial service in Iraq. OSI Agents Thomas Crowell, David Wieger and Nathan Schuldheiss died from an improvised explosive device. Brig. Gen. Dana Simmons, AFOSI commander, spoke during the memorial, challenging those present "to continue the fight and honor these heroes' sacrifice." (U.S. Air Force photo/Maj. John Sheets)

Soldiers in the Warrior Chapel Choir pray during the invocation of the “African-American/Black History Month” Observance in Iraq. By Spc. Dustin Roberts.

Servicemembers, civilians and contractors pray during an Easter sunrise service. By Maj. Sheldon Smith.

Soldiers and their military working dog partners take time to pray in honor of Kevin, a military dog who succumbed to cancer. By Spc. Howard Alperin.

Command Sgt. Maj. Keith D. Bragg and Lt. Col. David P. Jewell pray during an invocation given by Cmdr. Thomas Hall, Naval Postgraduate School chaplain, during the National American Indian Heritage Month observance. Photo Credit: Hiro Chang.

Unknown origin.

Chaplain (Brig. Gen.) Cecil R. Richardson gives the invocation during a wreath-laying ceremony in honor of the Flak Man crew at the Air Force Memorial, Arlington, Va. The wreath was placed by Edward McNally, the Bombardier of the B-24 Bomber, The Flak Man, in honor of the former crew members of the Flak Man who dedicated their lives to the cause of freedom. (U.S. Air Force photo by Senior Airman Rusti Caraker)

US Army Poster promoting one of the "five strengths" of the Comprehensive Soldier Fitness program. (US Army image)

Marines bow in prayer as they honor their fallen brothers during a memorial ceremony to honor Lance Cpls Joshua Birchfield and Cody Stanley, who were killed while conducting combat operations in Afghanistan. (U.S. Marine Corps photo by Pfc. Sarah Anderson)

US Army Chief of Chaplains (MajGen) Donald Rutherford leads Medal of Honor recipient Sergeant First Class Leroy Petry and President Barak Obama in prayer on 12 July 2011.

The Christian Navy Pennant flies over the US flag while aboard USS Trippe while in the Panama Canal Zone in the 1940s. The flag was to be flown above the National Ensign during religious services.

The Jewish Navy Pennant was the first non-Christian authorized flag in the Navy. It was added in 1975. The church pennant was to be flown above the National Ensign during religious services.

Service members and civilians stand together in prayer during the Mountain Top Experience on Signal Hill at Camp Liberty, Baghdad, April 26, 2010.