WASHINGTON — A watchdog group concerned with keeping apart religion and government is calling for the cancellation of an evangelical concert scheduled at Fort Bragg on Saturday.

Americans United for Separation of Church and State said the “Rock the Fort” event, put on by the Billy Graham Evangelistic Association, violates the Constitution and is targeting people for conversion.

“It’s not the Army’s job to convert Americans to Christianity,” said the Rev. Barry W. Lynn, executive director of Americans United. “This event is totally unacceptable and must be canceled.”

The group sent a letter to Army officials Thursday.

The Billy Graham Evangelistic Association, established to support the ministries of Billy Graham and his son Franklin, would not comment on the event, which will feature Christian musicians and a separate children’s program. A fact sheet published on the group’s website says the event will be a “clear presentation of the Christian Gospel.”

“Attendees will have an opportunity to respond to the Gospel Evangelistic message, be encouraged by Fort Bragg Chaplains and trained counselors from off-post Churches and on-post Chapels, and then be offered ongoing Biblical Spiritual Resiliency training at our military chapels and local churches,” the information sheet said.

According to the association’s website, other “Rock the Fort” concerts were held at Fort Jackson, Kentucky, in June and Fort Leonard Wood, Missouri, last October. Graham’s organization is planning to hold another event at Fort Jackson later this year.

The event at Fort Bragg event will be different, however, because for the first time the event will be open to the entire community.

Fort Bragg’s chaplain, Col. David Hillis, sent a letter to surrounding area churches to invite their congregations to the event and ask for help with its organization.

“Would you and your congregation join the Fort Bragg Unit Ministry Teams and me to be a crucial part of the success of this exciting outreach to the Fort Bragg community?” Hillis wrote.

Hillis defended the event in an interview, saying it was within the bounds of military rules and that attendance is totally voluntary. Hillis said soldiers are not obligated to go and that he would be willing to provide similar support if another faith wanted to hold a similar event on base.

In a message to earn support from the local churches, the Billy Graham Evangelistic Association posted that its involvement in the event should increase the size of its “congregation.”

“The Rock the Fort outreach is designed to channel new believers into your church, so you can encourage them to further spiritual growth. The future of the church lies in reaching and discipling the next generation,” the post said.

Americans United claims this type of evangelizing is going too far. “The Army has no business entering into a partnership with evangelical churches to help them win new members,” Lynn said.

— CNN Pentagon Correspondent Chris Lawrence contributed to this report.