Americans United for the Separation of Church and State said in a statement Thursday that the planned event -- a concert and other activities called "Rock the Fort" -- improperly enlists the military in a bid by the Billy Graham Evangelistic Association to win Christian converts.
The Charlotte-based ministry has sponsored similar events on military bases around the country. According to the BGEA's website, Saturday's event in Fayetteville is different because civilians as well as military personnel will be able to attend.
"Chaplains at the fort identified 20 churches in the area where most soldiers are involved," the site says. "The churches are now walking alongside chaplains from Fort Bragg, hosting training and praying for this event."
The site describes "Rock the Fort" as a chance to hear evangelists speak as well as listen to music by such Christian artists as Hawk Nelson and God Rocks. There's also a planned set of activities for children.
Bragg, which is home to the U.S. Army Airborne and Special Forces, has about 45,000 people living on post.
In a letter to Secretary of the Army John McHugh sent Thursday, lawyers for Americans United urged that the event be canceled.
"The military's participation in a religious event designed to proselytize soldiers and the community departs from the Army's obligation to maintain 'official religious neutrality,"' the attorneys wrote.
A call to the BGEA was referred to Fort Bragg. Calls to the post's Public Affairs Office were not immediately returned Thursday.
In its letter to McHugh, Americans United included a letter on Army stationery bearing the signature of Fort Bragg Garrison Chaplain David Hillis. The letter, dated June 2, is addressed to area Christian pastors, asking for assistance with "this unifying Christian event."
Americans United contends that chaplains in the military are restricted to holding religious services and making other accommodations for soldiers who want to practice their faith while serving in the Army.
"'Rock the Fort' is not an event designed to minister to the needs of soldiers unable to otherwise access religious services," the letter to McHugh says. "Rather, it is an event designed to proselytize soldiers and community members into the worship of Jesus Christ."