Wars have been waged over it. Soldiers have died in their foxholes praying. Troops justify going into combat because of their beliefs.
Religion can also be a power comfort and inspiration to those who choose to serve their nation.
Retired Master Chief Royal Weaver, who served 26 years in the Navy, said a majority of the sailors he served with -- as many as 90 percent -- professed belief in God even though many didn't go to church every Sunday.
"Most are believers, but you don't see them practicing it," he said.
Weaver said the threat of combat often makes those in the military think more spiritually.
"When you get put in a position where you might not make it through the day, you tend to rethink things," he said.
The United States military recognizes that religion can be as important to a person's identity as one's race or gender.
The Navy promotes a culture of diversity, tolerance and excellence by making every effort to accommodate religious practices, unless there are compelling operational reasons, said Cmdr. Ted Fanning, command chaplain at Naval Submarine Base Kings Bay.
The role of a chaplain is essential to the welfare and morale of those serving, regardless of religious belief, he said. The military has chaplains from many different faiths and denominations to accommodate the diverse makeup of those serving their country.
"There is no resource as unique as the Navy chaplain," Fanning said. "We eat, sleep, sweat, bleed and die with our sailors and Marines. We are there in the most significant moments of life: birth, death, marriage."
Most often the chaplain is the first to know when someone serving in the military is having a problem because he or she is reluctant to talk with a superior officer.
Chaplains are imbedded in the commands, making them accessible, approachable and safe.
"The unique role of Navy chaplains includes a sacred trust of maintaining absolute confidentiality," he said.
Fanning agreed with Weaver's perspective on how the threat of combat affects those serving in the military. The reality of death or imminent death "tends to focus the mind like nothing else," he said.
"The superfluous is stripped away and the mind hungers to know if there is 'more,'" he said. "The mission of the U.S. Navy is to defend our beloved country, our home. To that end, those who wear the cloth of our nation are ready and willing to give our most precious possession, our lives. Therefore, the author of life and death - God - naturally holds a prominent place in the hearts of many/most sailors and Marines."
Weaver said his belief in God strengthened while he served because of duty assignments in Europe, where he visited churches more than 1,000 years old. He also toured the Vatican.
"It impacts a person's faith," he said. "You really get to learn about what was fought over and what was fought over in the name of religion."
As he rose in rank, one of Weaver's responsibilities was making duty assignments. He didn't take into consideration religious holidays when he made his list of who would work that day.
But Weaver said he gave his subordinates the flexibility to swap duty assignments if it didn't interfere with their regular duties.
In some instances, sailors would ask Weaver not to assign them to work on a particular day because of an important religious holiday, and he could usually accommodate them.
Chaplains play an important role that goes beyond church services, weddings and funerals. Weaver said some sailors with problems would talk to a chaplain before he was aware there might be an issue that could interfere or distract a sailor on the job under his command.
"Everyone needs some kind of outlet," Weaver said. "A chaplain is better to talk to than a psychiatrist. You don't think of them of being in the chain of command."
Retired Navy Capt. Richard Strickland, who is also a Glynn County commissioner, served 20 years in the Navy. He said the military always came first, but faith played an important role with those who he served with.
"Chaplains are the backbone of the morale and well-being of our service members," he said. "They are there for tragedies, advice, counseling and family issues."