The same-sex marriage bill will be at the top of the Senate's agenda when parliament next sits, with MPs set to work overtime to legislate before Christmas.
There was an emotional start to the debate of Liberal senator Dean Smith's private bill on Thursday.
Politicians on both sides of the argument expressed their good wishes to couples who would be able to marry when the law is changed.
Debate will resume on November 27 with the Senate to sit until legislation clears, paving the way for a late-night session to push it through the upper house.
The bill can then be sent to the House of Representatives for debate, likely to start in the first week of December.
Attorney-General George Brandis believes the bill will pass the lower house before December 7, the last scheduled sitting day for the year.
Liberal Democrats senator David Leyonhjelm has proposed amendments which will allow civil celebrants to refuse to wed same-sex couples.
"Let's forge ahead and make the freedom to marry a reality but in a spirit of tolerance, understanding and personal liberty," Senator Leyonhjelm said.
He also wants to ensure government employees cannot refuse to solemnise marriages and give businesses the right to refuse to service weddings.
Prominent no campaigner and conservative crossbench senator Cory Bernardi has conceded the marriage law will be changed.
But he urged the parliament to consider concerns over freedom of speech and religion.
"You guys have the numbers to do whatever you want with this bill to go forward. I would only ask that you consider some of our concerns," Senator Bernardi told parliament.
Matt Canavan said he was hopeful he will be able to vote for an amended bill, with added protections for religious freedoms.
