The Marine Corps’ senior enlisted leader defended the Corps’ spiritual fitness initiative against critics who claim the Marines are trying to promote religion within the ranks.

Sergeant Major of the Marine Corps Ronald Green said Monday that spiritual fitness is about Marines recognizing that they will put their lives on the line for each other, despite any differences they may have had before joining the Corps.

“We set aside all of those differences to go forward and be willing to die for the very people that we love, for the nation, the Constitution and the flag that we honor,” Green said. “That’s the unique thing.”

Green acknowledged that there can be a religious aspect to spiritual fitness, but he stressed that fighting spirit also includes dedication to others before self, unity and the mission of keeping Americans safe.

The issue of “spiritual fitness” became controversial after Marine Commandant Gen. Robert Neller announced in October 2016 that the Corps would emphasize, “all components of fitness, particularly the physical and spiritual aspects.”

“Research indicates that spiritual fitness plays a key role in resiliency, in our ability to grow, develop, recover, heal, and adapt,” Neller wrote in ALMAR 033/16. “Regardless of individual philosophy or beliefs, spiritual well-being makes us better warriors and people of character capable of making good choices on and off duty.”

Soon afterward, a group that opposes proselytizing within the military threatened to sue the Marine Corps, claiming that spiritual fitness was a veiled attempt to promote Christian fundamentalism.

Since then, Marine Corps officials have steadfastly refused to provide information about exactly how Marines will learn about spiritual fitness.

Green acknowledged those concerns on Monday.

“We were challenged by the civilians – some of them out there – about, ‘Oh, you’re talking about God,’” Green said at a Pentagon press briefing with the senior enlisted leaders from all the service branches.

“Well, if you believe in God, yeah, we’re talking about that. But we’re really talking about that spirit regardless of where we come from.”

During his 34 years in the Marine Corps, Green said, he has never seen a Marine or sailor refuse to take part when a chaplain has said, “Let us pray.”

“We truly understand that’s an opportunity to dedicate ourselves to the soldier, sailor, airmen, Marine, Coast Guardsmen, National Guardsmen to our left and to our right – to say, ‘If you’re down on the battlefield, I’m coming to get you,’” Green said.