Melbourne Archbishop Denis Hart and CatholicCare have called for protection for faith-based groups that do not want to give adoption services to same-sex couples.

But, under the Andrews government's new laws, faith-based groups will not be granted exemptions to refuse services to same-sex couples seeking to adopt on the grounds of their sexuality.

The CatholicCare submission stated it risked breaching equal opportunity laws if it declined to provide adoption services to people based on sexual orientation.

"Adoption is about the best interests of the child, not about the rights for same-sex couples. It is not just or fair to impose such an agenda on adopted children," the submission said.

However, Equality Minister Martin Foley said CatholicCare was the only faith-based adoption agency that opposed same-sex adoption.

On Tuesday Archbishop Hart said he hoped "protection" would be provided to the CatholicCare to continue its work.

"The Catholic position on marriage and family holds that the well-being of the community and children are best served when they experience the love of both a mother and father in a safe, secure and stable relationship," he said.

Archbishop Hart said he acknowledged the "alternative point of view" but asked for respect from supporters of same-sex adoption so that CatholicCare could continue its work "in the tradition of the Catholic Church".

CatholicCare says it has facilitated five adoptions in the 2014/15 financial year compared with four the year before.

The government may face a challenge in getting the bill through the Victorian upper house where it only controls 14 out of 40 votes.

On Tuesday morning Opposition Leader Matthew Guy said he could not comment on the adoption bill because he had not yet seen the new legislation.

He has previously said Coalition MPs would be given a conscience vote but has also raised concerns about the bill's effect on religious freedoms.

The Greens, who command five critical votes in the upper house, support same-sex adoptions.

"Equality is equality. All MPs should be able to agree there's no room for treating gay couples any differently when it comes to adoption," Greens Leader Greg Barber said.

"Adoption is important because children need the security of having the parents they've grown up with as their legally recognised parents."

The Sex Party's Fiona Patten also supports the bill, which will give the government 20 votes in the upper house.

"As the aunty to a gorgeous niece who is growing up in a same-sex family this affects me personally," Ms Patten said.

"I hope this furthers the path to same-sex marriage."

Vote 1 Local Jobs MP James Purcell said the idea of same-sex couples being legalised recognised "sits reasonably comfortably" with him but he had yet to come to formal position on the bill.

The Shooters & Fishers Party, which holds two votes in the upper house, is yet to formulate a policy on the issues.

Democratic Labour Party MP Rachel Carling-Jenkins said she remained opposed to same-sex adoption. "I have no desire to contribute to the creation of another stolen generation, which is the path this legislation appears to put us on," she said.

Australian Christian Lobby Victorian director Dan Flynn said he would urge Coalition MPs to include an amendment to allow faith-based adoption agencies an exemption from the laws.

"We oppose gay adoption on the merits," Mr Flynn said. "We do assert that children are best with a mother and father figure."