Rome, Italy (CNN) -- The Vatican said a lawsuit accusing it and Pope Benedict XVI of covering up sexual abuse by a priest at a Catholic school in the United States has no merit.





"While legitimate lawsuits have been filed by abuse victims, this is not one of them," Vatican lawyer Jeffrey Lena said Friday. "Instead, the lawsuit represents an attempt to use tragic events as a platform for a broader attack."





The lawsuit by an unnamed Illinois man demands the Vatican release the names of thousands of Catholic priests that the suit says have "credible allegations of sexual misconduct" against them.





The alleged victim, who is now an adult, says he was molested by the Rev. Lawrence Murphy while a student at St. John's School for the Deaf, according to the complaint filed in U.S. District Court in Milwaukee, Wisconsin.





"The defendant, [the] Holy See, has known about the widespread problem of childhood sexual abuse committed by its clergy for centuries, but has covered up that abuse and thereby perpetuated the abuse," the suit says.





"The case against the Holy See and its officials is completely without merit," Lena said. "Most of the complaint rehashes old theories already rejected by U.S. courts."





Lena added, "With regard to Murphy himself, the Holy See and its officials knew nothing of his crimes until decades after the abuse occurred, and had no role whatsoever in causing plaintiff's injuries."





Benedict was named as a defendant because he has the ultimate authority to remove priests and because of his involvement in reviewing sex abuse cases when he was Cardinal Joseph Ratzinger, the suit says.





Peter Isely, Midwest director of the Survivors Network of those Abused by Priests, estimated the Vatican is investigating 4,000 cases of sex abuse by church employees.





The lawsuit aims to change church policies and practices that conceal sex offenders, Isely said.





"It's going to protect children, we hope, around the world," he said, "This is a historic day and hopefully this is going to result in historic changes."





Arthur Budzinski, a deaf man who said he was sexually assaulted and raped by Murphy, stood with Isely at a news conference Thursday.





He said the priest "may have stolen our bodies," but higher clerics such as cardinals, archbishops and the pope "stole our voices."





Budzinski, who is not a party to the lawsuit, made his comments in sign language and his daughter, Gigi, interpreted his words.





Murphy, who died in 1998, is believed to have molested up to 200 boys, Isely said.





The lawsuit said the church "knew that there was a high probability that these clerics would sexually molest more children, but sought to protect itself from scandal, sought to keep its income stream going, at the peril of children."





Murphy, it says, was a "top fundraiser and recruiter" for the church and the "Holy See wanted to retain Murphy's services."





The same Minnesota law firm representing the Illinois plaintiff also filed suit Wednesday on behalf of a Mexican resident who says he was sexually abused by a priest.





The suit alleges Catholic officials in Los Angeles, California, aided and abetted the abuse by moving the priest to different dioceses as allegations piled up against him.





CNN's Alan Duke and Hada Messia contributed to this report.
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