What about conservative Christian pastors? You're saying they should stop being celebrants? How do conservative Christians get married, then?
Ok. Quick lesson on how the marriage act works.
In Australia, there are two classes of marriage celebrants. There are civil celebrants, who don't take church services and are not allowed to discriminate in their services. And then there are ministers of religion, who are much more restricted.
As a minister of religion, I may
only marry adherents of my religion. And I may
only marry them according to the rites of my religious institution.
The day after same-sex marriage becomes legal in Australia, it will still be illegal for me to perform a same-sex marriage, because my religious institution has no rites for a same-sex marriage by which I could do so. This will not change except for churches or religious groups which choose to create and authorise rites for same-sex marriage (clearly, many won't).
In addition, a minister of religion has no obligation to marry any couple. I can already refuse to marry a couple if I disapprove of them for some reason (a civil celebrant doesn't have that right). I don't need to give them a reason. I don't need to have a good reason. It's totally at my discretion.
In all of the proposed changes to the legislation, no one is suggesting changing the conditions under which ministers of religion may solemnise weddings. So there is no question of ministers of religion having a problem here.
My earlier comment was only in regard to civil celebrants.