Non-Orthodox leaders this week upped the pressure on the Board of Deputies to justify a campaign to reverse last year's Supreme Court ruling on JFS.
In a joint statement reacting sharply to recent comments by Board president Vivian Wineman, the Reform, Liberal and Masorti movements warned it was "premature" to talk of legal change.
They declared: "We are not persuaded that the decision of the Supreme Court has presented the Jewish community with insurmountable difficulties, and consider talk of a 'threat to welfare provision and even possibly religious services' to be at best unfounded and at worst irresponsible."
They were also "not convinced by the statement of the Board of Deputies and others that it is necessary to change the law 'to protect the community' since no case has yet been made concerning what the community needs protection from".
The statement was signed by Reform head Rabbi Tony Bayfield, Liberal chief executive Rabbi Danny Rich and Masorti executive director Michael Gluckman.
In a recent address to the Board, Mr Wineman spoke of concern "that if providers of educational services cannot offer them to Jews on a preferential basis then the same logic could be applied to providers of welfare services such as care homes or even possibly religious services. The Board would like to therefore to see the law changed to protect the community."