The lawsuit, filed in U.S. District Court in Rome, claims the Georgia law effectively "criminalizes fundamental religious activities" for sex offenders and bars them from serving as a choir member, secretary, accountant or any other role with a religious organization.
"Even helping a pastor with Bible study or preparing a meal in a church kitchen will subject (sex offenders) to prosecution and imprisonment," the complaint said.
It is the latest of a growing list of legal challenges targeting Georgia's strict sex offender statute, which was hailed by supporters in 2006 as one of the toughest in the nation but has since been the frequent focus of lawsuits contending it is far too restrictive.
The main portion of the measure bans sex offenders from living, working or loitering within 1,000 feet of just about anywhere children gather. That includes schools, parks, gyms, swimming pools and the state's 150,000 school bus stops.
The original version of the law banned sex offenders from working at churches, but when it was retooled this year, supporters slipped in a provision also banning them from volunteering at houses of worship. Doing so could risk a penalty of 10 to 30 years in prison.
The changes were adopted with little debate in April at the urging of Republican lawmakers who said they will help protect Georgia's children and prevent the state from becoming a "safe haven" for sex offenders.
"I have not had one prosecutor, one judge, one sheriff, one mama, one daddy, one grandparent coming down here telling me to repeal the residency requirements on sex offenders," state Rep. David Ralston, R-Blue Ridge, one of the measure's sponsors, told House lawmakers during the session.
Some national advocacy groups have also rallied to defend the measure.
"Giving sex offenders any title or position in a religious organization is like giving a gun to a bank robber. Why take the risk?" said Barbara Dorris, of the Survivors Network of those Abused by Priests.
Critics have launched a slew of lawsuits over the past two years claiming the law is unconstitutional, and federal judges are already considering challenges targeting the school bus stop portion of the law and another provision that could evict offenders who live near churches.
The latest challenge, filed by the Atlanta-based Southern Center for Human Rights, says the measure deprives Georgia's sex offenders of the "rehabilitative influence" of religious activity.
"Certain people on the sex offender registry should not work with children in a church setting or elsewhere," said Sarah Geraghty, an attorney with the center. "But criminalizing the practice of religion for all 15,000 people on the registry will do more harm than good."
The lawsuit centers on five sex offenders who fear the new provision, which goes into effect July 1, will ban them from participating in many religious functions.
Among them is Omar Howard, 33, who is on the registry after he was convicted of false imprisonment of a minor during a 1993 burglary.
He got involved in a Christian ministry during his 14-year prison sentence and became a volunteer at several churches after his release last year. He's not sure whether the law will allow him to help prepare for revival meetings, serve on church committees or sing in the choir, which he feels is part of his calling.
"What really can I do? This law cripples me. All I can do is go to sermons and leave. Why am I a threat to exercise my faith?" he said.