A U.S. army chaplain has come under attack for sharing Pastor John Piper's new book, "Coronavirus and Christ", with calls for him to be court-marshalled.

Fierce calls have been made to discipline Senior Army Chaplain Col. Moon H. Kim, who is the command chaplain of U.S. Army Garrison Humphreys in South Korea.

The Military Religious Freedom Foundation (MRFF), a national legal organisation that advocates for a strict separation of church and state in the military, has contacted U.S. Secretary of Defense Mark Esper demanding that Chaplain Kim be punished. They are outraged after Kim sent out an email containing a PDF copy of John Piper's new book "Coronavirus and Christ" from his official military email address to 35 other chaplains.

MRFF says it is representing 22 clients, who are all Christians upset at Kim's email. A number of the 22 are members of the LGBT community who say they "do not subscribe to the ultra-conservative/Reformed/evangelical Christian theology of John Piper."

One section of Piper's book says "some people will be infected with the coronavirus as a specific judgment from God because of their sinful attitudes and actions."

In Kim's email to his fellow chaplains he wrote: "This book has helped me refocus my sacred calling to my savior Jesus Christ to finish strong. Hopefully this small booklet would help you and your Soldiers, their Families and others who you serve."

MRFF Founder Mikey Weinstein has insisted Kim's email amounts to an absolute endorsement of Pastor John Piper's entire book and the teachings within, and that the book "pushes the belief that the coronavirus is God's judgment."

Weinstein argues that Chaplain Kim's email was sent to his subordinate chaplains, and that he was a "man in a position of substantial power and influence over them."

Therefore, MRFF says, the email violated the Department of Defense and Army equal employment opportunity policies.

Meanwhile, Mike Berry, who is general counsel for First Liberty Institute, an organization that defends the First Amendment rights of military members, has oppositely argued that Chaplain Kim was within his rights to send the email.

Berry has said, "The MRFF is not only going overboard, it is showing its true colors by asking the Pentagon to punish a chaplain for engaging in constitutionally protected activity."

He added, "Congress has recently and repeatedly taken actions to protect chaplains to share their religious beliefs."

"The Constitution and federal law protect chaplains (and service members) who share their religious beliefs," Berry said. "Our brave service members should be offended that Mikey Weinstein thinks they are so delicate and frail that they are incapable of hearing something with which they might disagree. Quite the contrary, the vast majority of service members with whom I served, whether senior or subordinate, were smart enough to decide for themselves."

First Liberty Institute has said it is willing to provide Chaplain Kim with free legal representation if he does become subject to any type of disciplinary action for the email.