Australian PM Malcolm Turnbull is one of those supporting a yes vote in an upcoming postal vote.
Even if the same-sex couples can marry, it will not be marriage equality.
Australians will have a verdict on same-sex marriage by mid-November after the High Court threw out a legal challenge to the Turnbull government's postal survey and ruled it can proceed.
Bree, a same-sex marriage supporter from Perth, wrote a heartfelt note to the man saying that she had decided against ticking "yes" on his form because she did not want to strip the man of his "voice". "Please don't leave this change to other people".
"I wish to state quite clearly that the Catholic Church, through its official teaching, can not support proposals for the changing of the legal definition of marriage to include same-sex couples", he wrote.
The legislation was introduced because the survey is not covered by the usual safeguards governing elections in Australia. "We pray and fast in a special way for our nation's leaders, we pray that they will uphold God's plan for marriage in our nation", Bishop Kennedy said.
Turnbull, the only serving prime minister to attend the Sydney's Gay and Lesbian Mardi Gras, quoted former British Prime Minister David Cameron at a weekend "yes" campaign launch in arguing that conservatives should support gay marriage.
All postal papers will be sent out by September 25, and must be mailed back by October 27 for your vote to count.
Both sides of the debate fired the starting guns on Thursday afternoon, promising to run respectful campaigns.
Speaking at a graduation ceremony at the University of Adelaide on Wednesday, Mr Kirby, who is gay, says the survey shows once again that LGBTI Australians are singled out for discrimination and unequal treatment under the law. And I think parental rights should be respected, ' he told Buzzfeed.
Coalition for Marriage spokesman Lyle Shelton, who ordinarily runs the Australian Christian Lobby, said his campaign would focus on religious freedom and what kids were taught in schools.
If you haven't got your same sex marriage survey in the post yet, don't panic because it's on the way.