The Military Religious Freedom Foundation has engaged in some pretty despicable behavior over the years — from demanding that the Baby Jesus be removed from military bases to complaining about Bibles on Missing Man tables.

But their recent attack on the Airmen at Grand Forks Air Force Base in North Dakota is so outrageous even the Grinch is wondering, “Dude, what the hell?”

The MRFF is infuriated because Airmen were encouraged to volunteer with the Salvation Army to hand out food baskets and gifts to families in need.

MRFF founder Mikey Weinstein said he was contacted by 40 military personnel who felt humiliated and oppressed by the invitation to assist the Salvation Army.

“There’s no problem with the Salvation Army,” he told the Grand Forks Herald. “The problem is with the Air Force singling it out and endorsing a nonfederal entity.”

Weinstein, in a letter to the Grand Forks AFB public affairs office, called the invitation a “disgraceful civil rights violation.”

To their credit, it appears the Air Force base has pretty much ignored Weinstein’s Scrooge-like rantings.

“The problem is it’s during the duty day,” Weinstein told the newspaper. “That’s when the American people are paying for members of the military to provide national defense, not support one particular version of the Gospel of Jesus Christ through an organization like the Salvation Army.”

First Liberty Institute jumped to defend not only the Air Force base but also the Airmen who volunteered for the Salvation Army’s Christmas event.

“Such participation is not only permissible, but is consistent with the highest standards of the Air Force mission,” First Liberty Institute attorney Michael Berry wrote in a letter to base officials.

First Liberty rightly noted that MRFF’s complaint is unfounded and unsupported by the law.

“The Constitution does not prohibit active duty service members, reservists or Department of Defense employees from voluntarily participating in community service events with the Salvation Army,” Berry wrote.

And military regulations clearly point out that volunteer service is permitted so long as there is no Department of Defense endorsement of any non-Federal entity.

“Excluding the Salvation Army purely because of its religious identity and character sends the wrong message, and exhibits the kind of anti-religious hostility against which the Constitution guards,” Berry noted.

How sad that the cold-hearted Grinches who lurk in the dark shadows of the Military Religious Freedom Foundation’s headquarters got their tinsel in a twist because Airmen wanted to make sure needy children would be able to celebrate Christmas.