Christopher Carey, 29, and his wife Valerie, 27, were taken to a psychiatric ward Monday and charged with murder. The husband was later transferred to jail.
The Careys were arrested after they were spotted wandering the street naked in the freezing cold with a 7-year-old girl and 2-year-old boy.
The older child provided detectives with information that led investigators to the motel where the 6-year-old was discovered, police spokesman Sgt. John Quigley said.
Quigley said the adults indicated they were conducting a ritual that "had something to do with undemonizing the child."
The relationship between the two adults and three children was not immediately clear. Quigley said DNA testing would be conducted to determine whether the children were related to the Careys.
Christopher Carey was being held Tuesday at Fulton County Jail after waiving his first court appearance. His next hearing was scheduled for Feb. 3.
Valerie Carey still was being held at a hospital, said jail spokesman Lt. Clarence Huber. Both also face charges of cruelty to children, public indecency and obstruction of police.
The surviving children were placed with the Division of Family and Children Services.
The two adults apparently had been transients living at the motel for an extended period, possibly through assistance from a church, Quigley said.
If the girl was the victim of an exorcism, hers would be at least the sixth such death in the past nine years.
On March, 8, 1995, Kyung-A Ha, 25, was beaten severely during a night-long exorcism conducted by members of the Jesus-Amen Ministries in San Francisco. Kyung Jae Chung was killed in a July 4, 1996 exorcism in Los Angeles.
In 1997, a 5-year old girl in Bronx, N.Y., was forced to drink a mixture of ammonia, pepper, vinegar and olive oil because her mother and grandmother thought she was possessed. Gagged with duct tape, she died.
Charity Miranda, a teenager from Long Island, N.Y., was suffocated in a plastic bag by her mother and sister during a ceremony in 1998. Terrance Cottrell, an 8-year-old, was beaten to death during an attempted exorcism in Milwaukee last September.