The Tasmanian Government's proposed changes to the Anti-Discrimination Act has raised the ire of conservative groups and same-sex marriage advocates.

In the lead-up to a national plebiscite on same-sex marriage, the State Government has proposed changes that would create a "reasonableness test" within the act.

Church groups will have more freedom to speak out against same-sex marriage under the changes, as it would provide an exemption to anti-discrimination if the act is for religious purposes.

Under the proposal, the Anti-Discrimination Commissioner would also have to reject a complaint if it could not have been predicted an act would cause offence.

Premier Will Hodgman said the changes would allow "genuine protection of freedom of religion by striking a fairer balance between the right of free speech and the need to protect people from unlawful conduct".

He said the current act was not fulfilling its role in allowing free speech while providing protections.

"The Government's view is that our laws ... don't currently get that balance right," he said.

The proposal would also mean the state's Anti-Discrimination Commissioner would have to reject a complaint if it could not have been predicted an act would cause offence.

"This change will allow the complaint to be quickly resolved and rejected in circumstances where there is a valid defence," Mr Hodgman said.

'Allowing hatred to be acceptable under guise of religion'

Prominent gay rights advocate Rodney Croome said he staunchly opposed the plan, arguing the act did not need to be changed.

"There's already a reasonableness test in the Anti-Discrimination Act," he said.

"What the Government is proposing is allowing hatred to be acceptable under the guise of religion.

"It will give a green light to those who want to exploit the proposed plebiscite on marriage equality to stir up hatred against lesbian, gay, bisexual and transgender people."

Mr Croom said the proposal created a double standard because "the Government is saying that humiliating and denigrating other people is wrong, unless it's done in the name of religion".

'Government has not backed free speech enough'

The Australian Christian Lobby's Mark Brown welcomed the Government's thinking, but said it did not go far enough.

"While we are very happy with the intention of the changes we believe they've missed the mark, in that this is really an issue about free speech rather than religious practice," he said.

The lobby said sections of the act relating to causing offence needed to be totally removed before the planned plebiscite.

"This leading into a plebiscite is going to be important for everybody to have the right to free speech, and some people will be offended," he said.

"That's what happens in a normal debate - people don't go out to offend people but everyone needs to have that freedom.

"In countries where same-sex marriage is legislated, like Canada for instance, it has become an offence to even say that children deserve to have a mother and a father where possible. We don't want to see that happen here."

The legislation is expected to be tabled soon.

The changes come after transgender activist Martine Delaney lodged a complaint about a Catholic Church booklet opposing same-sex marriage.

Ms Delaney withdrew her case earlier this year, citing a lengthy tribunal process.