The Catholic Church says it did not intend to cause offence after the Tasmanian Anti Discrimination Commission ruled it has a discrimination case to answer over its booklet on same-sex marriage.

The case has raised concerns about freedom of speech ahead of a national debate on same-sex marriage.

Activist and Greens candidate Martine Delaney made a complaint about the booklet to the Anti Discrimination Commission.

She said the Don't Mess with Marriage booklet, which was distributed through Catholic schools, was offensive, humiliating and insulting.

"It makes several statements which suggest that children being raised in same-sex relationships are not healthy," she said.

The Anti Discrimination Commissioner has decided the Catholic Church and the Tasmanian Archbishop have a case to answer.

Ms Delaney said she was relieved her complaint was not dismissed.

"My initial reaction was like it's a bit of interim joy, interim pleasure, that the Commissioner hasn't dismissed it out of hand," she said.

Catholic Archbishop of Hobart Julian Porteous said any offence was not intended.

"The first thing I want to say to Martine is look, I regret if you've felt that, it was not my intention and not the intention of the Catholic Bishops to cause that offence," he said.

But the Archbishop said the booklet would not be withdrawn.

Church argues it is 'gravely unjust' to: Legitimise the false assertion that there is nothing distinctive about a man and a woman, a father or a mother

Legitimise the false assertion that there is nothing distinctive about a man and a woman, a father or a mother Ignore the particular values that real marriage serves

Ignore the particular values that real marriage serves Ignore the importance for children of having, as far as possible, a mum and a dad, committed to them and to each other for the long haul

Ignore the importance for children of having, as far as possible, a mum and a dad, committed to them and to each other for the long haul Destabilize marriage further at a time when it is already under considerable pressure

Destabilize marriage further at a time when it is already under considerable pressure Change retrospectively the basis upon which all existing married couples got married Source: Pastoral letter on the same sex-marriage debate

"It's just simply us presenting what we believe to be right and true and good," he said.

Same-sex marriage opponents claim the freedom to voice their beliefs was under threat by the discrimination case.

On Thursday night the Senate voted down a motion moved by Tasmanian senator Eric Abetz supporting the right of the church to distribute the booklet.

"It is vital that there be an expression from this Senate about the right for freedom of speech and right to express certain views," Mr Abetz told the Senate.

The Church was asked to respond to the complaint before the Commission decides if a hearing should be held.

Archbishop Porteous said he was hoping the issue would be resolved through mediation.

Ms Delaney said she was hoping for an apology.

"The church is entitled, as we all are, to freedom of speech but there's an inherent responsibility with that, that you cannot do it in a manner which is offensive and insulting and humiliating," she said.