When the Military Religious Freedom Foundation (MRFF) sent a letter of complaint to a Marine Corps base in Hawaii, asking the base commander to remove a sign that says "God bless the military," the civil rights watchdog group was with defiance.

The letter was sent last month to Col. Sean Killeen, the commanding officer of Marine Corps Base Hawaii, according to Christian News. The group had an issue with a sign near the marina that reads, "God bless the military, their families, and the civilians who work with them." The sign was reportedly put up after the tragic Sept. 11, 2001 attack on the United States.

Blake Page of MRFF said the sign is a violation of the Establishment Clause of the US Constitution. He suggested that the sign be moved to the chapel, or be removed altogether.

"This sign is a brazen violation of the No Establishment clause of the Constitution, as it sends the clear message that your installation gives preference to those who hold religious beliefs over those who do not, and those who prefer a monotheistic, intervening God over other deities or theologies," Page wrote.

"We recognise the value that religious activity brings to the lives of many," he further said, "However, this sign is not in keeping with the time, place, and manner restrictions required by law (or) for any military commander to bolster religious principles through the official authority given to their rank and position."

After receiving the e-mail, the religious liberties group Alliance Defending Freedom (ADF) immediately sent Killeen an email, saying the MRFF's demands should not be heeded because they are unconstitutional.

"As it stands, the sign is not grounds for an Establishment Clause violation. However, removal of the sign would certainly be in violation of the Establishment Clause, showing preference for no religion over religion," Director of Military Affairs Daniel Briggs wrote.

"Our nation has many constitutionally permissible reminders of our historical and cultural roots, from our national motto, 'In God We Trust,' to 'so help me God' in the Commissioned Officer's Oath to the presidential proclamations accompanying each National Day of Prayer," he said.

After much thought, Killeen decided to keep the sign. Last Friday, he wrote a reply to the MRFF: "Several Supreme Court cases and other federal cases, to include the 9th Circuit, support the conclusion that the message on the sign does not violate the Establishment Clause of the US Constitution. 'God bless' is commonly used in our culture in a number of contexts and there are numerous references to God in this nation's symbols, songs, mottos and oaths.

"To date, we have not received any direct complaints concerning this sign from service members or reports of service member complaints through any official chain of command," Killeen added. "We will always support all service members' rights to pursue and practice their own belief sets, whether religious or not."