A religious freedom group is pushing back against an atheist organization's efforts to end "unconstitutional" prayers and Bible readings presented by a chaplain during ceremonies at an Air National Guard base in New Hampshire.

First Liberty Institute, the largest legal organization in the nation dedicated exclusively to defending religious freedom for all Americans, on Tuesday sent a letter to Col. James Ryan, the commanding officer at Pease Air National Guard Base.

In the letter, the organization reminded him that federal law, military regulations, and the Constitution all allow prayer and Bible readings by chaplains at military events - despite with that the Freedom From Religion Foundation (FFRF) says.

"The FFRF's position and legal argument are incorrect. Federal law, military regulations, and court precedents belie the FFRF's specious claims. Uniformed chaplains are clearly permitted, indeed protected, when they offer invocations at military functions," senior counsel Mike Berry wrote in the letter, which was made available to The Gospel Herald.

Referencing the Religious Freedom Restoration Act (RFRA) and the National Defense Authorization Act, as well as the Department of Defense (DoD) instruction entitled "Accommodation of Religious Practices Within the Military Services," Berry said that "the DoD must accommodate individual expressions of religious belief, which undoubtedly include a military chaplain's invocation."

Last month, FFRF - an organization known for its staunch opposition to Christianity - sent a letter to base leadership to warn that the inclusion of the chaplain-led invocations and Scripture readings at official Air National Guard ceremonies is unconstitutional.

In the letter, the organization said it had been contacted by an anonymous guardsman who was "concerned" about the "unnecessary, divisive, coercive and insensitive" inclusion of prayer.

"Christian prayers delivered at an official military event violate the Constitution's mandate of government neutrality between religious beliefs," FFRF charged. "Any prayer-including non-denominational prayer-violates the required neutrality between religion and nonreligion."

"By imposing prayer on its guardsmen at mandatory events, the Air National Guard is violating the constitutional limits on government religious endorsement," it said.

FFRF added that the invocations exclude those who don't identify as atheists: "The Air National Guard must refrain from lending its power and prestige to religion, amounting to a government endorsement that excludes the over 23% of military personnel who either express no religious preference or are atheists," it said. "It is also simply insensitive for a government employer to inflict prayer on employees regardless of their personal beliefs."

FFRF concluded: "We ask that you protect the rights of conscience of every guardsman by ending the practice of including prayers at official ceremonies and other events," it wrote. "Please inform us in writing of the actions that you intend to take to address this issue so that we may notify our complainant."

In a statement, Chaplain (Colonel) Ron Crews, U.S. Army (Retired), Executive Director for the Chaplain Alliance for Religious Liberty, urged President Donald Trump to work toward protecting religious freedom.

"Military chaplains exist to ensure all service members have the right to free exercise of their religion," he said. "The prayers and Bible readings they offer at Pease Air National Guard Base are one of many ways they faithfully discharge that duty. Their faithful service should be respected, not attacked."

"We hope our Commander in Chief will reverse this trend toward religious hostility so that America's military can remain strong and resilient," Berry said.