Demon Child: the Exorcism of John's Sister

Is it moral to perform an exorcism on a child if the exorcism causes harm to that child?

Father Malloy never imagined that he would be faced with that question. He had never believed in demon possession. At least, he didn't believe that demon possession occurred in current times. When John Horne comes to him for help, Father Malloy thinks that he will be providing counseling to the Horne family, nothing more. What he discovers at the Horne's home in rural Tennessee threatens both his faith and his life.