FEDERAL Independent MP Bob Katter has told a rally at Parliament House same-sex marriage should not be taken seriously and deserves to be ridiculed.

Mr Katter was among a handful of federal MPs who addressed a gathering of several hundred people attending the pro-marriage rally today.

"Truly this proposition deserves to be laughed at and ridiculed. It doesn't serve any serious treatment," he said to cheers and thunderous applause.

The Queensland MP harked back to a time when the word "gay" had a different meaning from that of today, describing it as one of the most beautiful words in the English language.

After quoting the poet Alexander Pope, Mr Katter said "nobody has the right to take that word off us."

Liberal MP Kevin Andrews told the rally that allowing gays and lesbians to marry destroyed the institution itself.

"This is a destruction of marriage, not simply a redefinition," he said.

So far this year all state and territory divisions of the ALP, with the exception of NSW, have passed motions of support for full marriage equality.

Coordinator of the National Marriage Coalition, Gerard Calilhanna, said the next challenge for the pro-family lobby was Labor's national conference in December.

"They must not relax their party's stance in any way on marriage at the national conference," he said.

"We must make them pay for this if they do."

"Even if they go to a conscience vote ... that means a lack of confidence in marriage itself."

He described same sex marriage as "nothing less than the overthrow of marriage in Australia."

Nationals Senate leader Barnaby Joyce said his four daughters would be affected if same sex marriage was allowed.

"We know that the best protection for those girls is that they get themselves into a secure relationship with a loving husband and I want that to happen for them.

"I don't want any legislator to take that right away from me."

Labor MP John Murphy said relationships between same sex couples were not the same as relationships between men and women.

"My electorate accepts that all people are equal, but my electorate also accepts, in fact rejects, that not all relationships are equal", the western Sydney MP said.

Meanwhile, a new poll has found that 53 per cent of Christians in Australia believe same sex couples should be allowed to marry, while 41 per cent were opposed.