Cesar Pastrana pleaded guilty Friday in a Cobb County courtroom.
Authorities said Pastrana met victims while volunteering at NorthStar Church in Acworth. Investigators said Pastrana confessed to police after initial allegations were made against him.
The families of the victims have filed a lawsuit against the church, arguing the abuse could have been prevented.
Church officials told WSB-TV that they could not comment because of the ongoing investigation. Pastrana is an illegal immigrant from Mexico.