Turnbull government frontbenchers are publicly disagreeing with George Brandis after the Attorney-General rejected conservative arguments against same-sex marriage and said he would not be "tricked" into debating wider issues of religious freedom.

On Sunday, Senator Brandis said religious freedoms would continue to be protected and insisted the upcoming postal survey was only about allowing two people of the same gender to marry.

But conservative frontbench colleagues Zed Seselja and Angus Taylor have disagreed, warning of the consequences of change.

Former prime minister Tony Abbott has again drawn the public ire of his high-profile sister for his own argument about the broader implications of same-sex marriage. Liberal councillor Christine Forster rejected her brother's claim that changing the Marriage Act raised questions about "gender fluidity".