Mr McCoskrie told APNZ he was aware of other celebrants who had adopted the same stance, and said he had been "overwhelmed with support'' since announcing his decision.
Auckland celebrant Kathrine Fraser, immediate past-present of the Celebrants Association of New Zealand (CANZ), said a survey at the time of the law change found most celebrants were in favour of it.
She said it had also been made clear that while celebrants were empowered to marry couples, they were not compelled to marry anyone they didn't wish to.
Couples generally looked for a celebrant who they connected with and who shared their outlook, so a same-sex couple was unlikely to choose a celebrant who was uncomfortable with gay marriage, she said.
There was plenty of choice for same-sex unions, particularly as all civil union celebrants had been given the opportunity to transition to being marriage celebrants with the change in law.
Celebrant Rei Hagan, co-chair of CANZ Waikato branch, said she wasn't aware of any celebrants who had resigned as a result of the law change.
"I haven't heard of a single person resigning for that reason. Not one.''
She also wasn't aware of any celebrants who had concerns about being required to marry same-sex couples.
Figures from the Department of Internal affairs show 361 same-sex couples married in New Zealand between August 19, 2013, when the new law came into force, and December 19.