Christian lobby groups have attacked the ACT government's religious vilification bill, claiming the legislation will undermine freedom of speech and lead to drawn out legal battles.

The Australian Christian Lobby and FamilyVoice Australia, a Christian ministry promoting ''family, faith and freedom'', say they want the bill shelved or abandoned.

But Attorney-General Simon Corbell defended the legislation, which will add religion to the list of vilification offences in the territory's Discrimination Act.

Mr Corbell said claims the proposed laws would result in religious disputes ending up in court were incorrect and that opponents of the bill ''failed to understand how the Discrimination Act works''.

But Ros Phillips, the national research officer for FamilyVoice Australia, said a five-year case against two Christian pastors in Victoria, that was ultimately unsuccessful, was an example of how similar laws had failed.

''This sort of ridiculous situation was only made possible by that law,'' she said.

''I certainly hope that our lawmakers in the ACT look at what's happened elsewhere and don't go ahead.''

Mrs Phillips said if the bill was approved by the Legislative Assembly, it should include a clause that would allow for truth as ''a complete defence against any charge of religious vilification''.

Australian Christian Lobby chief of staff Lyle Shelton said although vilification of any kind should be ''condemned'', the proposed laws could lead to social disharmony, rather than social cohesion.

''It's something that's had a negative impact in Victoria in terms of promoting harmony between religions,'' he said. ''We just can't understand why the ACT would go down this path when the only example Australia has had with these laws led to a long, drawn out legal battle that did nothing for social cohesion.''

Mr Shelton said he was also concerned about the government's failure to consult Canberra's Christian community about the impact the laws might have on debate between religious groups.

''It provides a legal stick for people to use if they feel offended or vilified in the course of robust public debate,'' he said.

But Mr Corbell said the changing the Discrimination Act would not make religious vilification a crime under the territory's criminal code.

The Attorney-General said complaints would be heard by the Human Rights Commission, which would try to achieve reconciliation between the parties involved.

If the HRC couldn't resolve the matter, it would be referred to the Civil and Administrative Tribunal which, in the ''most severe of cases'', could recommend payment of damages.

Mr Corbell said the Discrimination Act also included clauses that protected freedom of speech and the right to ''reasonable and honest'' expression.

''It would not be unlawful for someone reasonably and honestly to contrast their religious perspective with that of another,'' he said.

''The issue is for groups that go beyond reasonable and honest debate and seek to incite hatred towards or vilification of other religious groups.''

Mr Corbell said he wanted to know why some groups seemed to view the bill as ''a threat''.

''Why are people so afraid of providing a legal protection that allows religious beliefs to be respected and openly practiced?'' he said.