"Until the Army withdraws all official support and approval from witchcraft, no Christian should enlist or re-enlist in the Army, and Christian parents should not allow their children to join the Army," said Paul M. Weyrich, president of the Free Congress Association.
The Christian Coalition, Traditional Values Coalition and the American Family Association are among the groups initiating the ban. The Christian Coalition alone boasts 2.1 million members.
The controversy started with news reports that witches were holding rituals on the nation's largest military installation, Fort Hood in Killeen.
Although a congressman demanded the practices be banned, Fort Hood officials said last month that the pagans could continue their worship.
The base sanctioned Wicca - a nature worship that claims roots in pre-Christian Europe - three years ago by providing space for rituals. Wiccan groups have since sprung up on U.S. military bases worldwide. The conservative groups also are lobbying the Army to change its chaplain handbook, which includes the Church of Satan among sanctioned religious groups.
Mr. Weyrich called that inclusion "a direct assault on the Christian faith that generations of American soldiers have fought and died for."
John Machate, coordinator for the Military Pagan Network, told the Austin American-Statesman that the boycott was more of "a direct attack on the Constitution of the United States," which includes freedom of religion in the First Amendment.
Adherents of Wicca believe in gods and goddesses and celebrate cycles of the sun and moon.
Images of witches as women who cast evil spells was introduced in ancient times by the Roman Catholic Church to describe heretics and has nothing to do with modern witchcraft, proponents say.