"At the core of their concern is the opinion their daughters may be exposed to messages or values that they do not personally agree with."
The letter, seen by news.com.au, was sent at a time when the national Safe Schools programme - designed to protect same sex attracted, intersex and gender diverse students - is under attack and as Australians prepare to vote on a same-sex marriage plebiscite.
Ms Herman, a former student at the school, said staff and students "from many faiths, ethnicities, sexual orientations and political convictions proudly call Kambala 'my school'".
"Kambala does not discriminate, positively or negatively, when hiring staff... All staff, regardless of their role, are selected on merit, empathy and their commitment to supporting the Christian ethos of the school.
"We are a school community whose composition reflects the diversity of the broader community that we service. We exist together as a community that wants to be defined more by how we care for each other than how we might discriminate."
She said "love isn't an optional extra" at Kambala, rather: "We practice love even when it is hard to do. We take the command of Christ seriously when He said, 'Love your neighbour as yourself'."
GP and civil rights advocate Kerryn Phelps spoke with news.com.au about the school's powerful response.
"My first reaction was 'Don't tell me this is still going on'. Then I thought about how fantastic the school's response was. They're a role model for school leadership in dealing with a small minority of people who can make others' lives such a misery."
Dr Phelps said the reaction from parents had the potential to be harmful on a number of levels.
"First, it sends the overt message that there's something wrong with gay teachers teaching kids, which we know is not the case," she said.
"Subliminally, it sends a message to young people dealing with their own sexuality that that's something wrong with them. It also sends a message that teachers should be quiet about who they are in their private lives."
Dr Phelps said she expected the same sex marriage plebiscite, expected to be voted on in February next year, could expose young people to similarly harmful views.
"It's not going to be a debate, it's going to be an opportunity to make life difficult for people."
Sydney filmmaker Maya Newell, who created a documentary titled Gayby Baby about children of gay parents - a film that was screened in Sydney schools last year, said she was saddenned by the parents' reaction.
"It is sad that, yet again on Wear It Purple Day, the one day a year that celebrates Australia's LGBTIQ youth, we have to hear controversial new stories that throw that celebration into question.
"At Gayby Baby, we applaud the proactive response of Ms Herman at Kambala who took a strong stance to remind parents that inclusion and diversity are centre to the school ethos. How amazing that Kambala students have heard the message loud and clear that regardless of their sexual preference or gender identity, they are valued members of their school community.
"Let's hope all principals can follow her lead."
Kambala has been approached for comment.