The Rev Dr John Ross, a former moderator of the Free Church of Scotland, said plans to have a named person for every single youngster were "the sort of thing we would expect in a fascist or Marxist regime".
He is one of seven leading figures from the Free Church who have written to First Minister Alex Salmond, urging him to amend the legislation.
The proposal for every child to have a named person appointed for them is included in the Children and Young People (Scotland) Bill, expected to be approved at Holyrood next week. The Bill says a named person, such as a health worker or headteacher, would be responsible for safeguarding a child's welfare and liaising with family.
The Free Church figures including current moderator the Reverend Angus Howat, are the latest to voice concerns about the move, following The Law Society of Scotland and the Faculty of Advocates.
A Government spokesman said the move aimed to offer "early support, with a single point of contact, to help prevent emerging concerns becoming more acute". But Dr Ross, a minister in Drumnadrochit in the Highlands, said: "If this legislation is not amended, the Scottish Government will make itself the judge of every parent in this land."
He urged Mr Salmond to "do everything in his power to get rid of this snooper's charter and restore some common sense".
Bill Alexander, director of health and social care at Highland Council, where the system already operates, said: "The named person role was not introduced by the Scottish Government, but developed from practice. It operates effectively, and enables agencies to respond more quickly to parents who raise concerns about their child's wellbeing."