A leaked document reveals Bethlehem College will use biological pronouns for students, and the school needs to approve that their name "aligns with their biological sex".
In response to the leaked document, the school said "it's not wise or kind" to support children down a path of experimental hormonal and surgical medical interventions.
The document states that "the biological sex of a person is determined at conception to be male or female and their gender identity should align with their biological sex".
Described by the school as a "working document", it was the "summary of beliefs relating to gender as a school of Special Character".
But the school's stance has come under fire from Pride advocate Gordy Lockhart, who said in his opinion the document was ''discrimination ... segregation, homophobia all rolled into one. It's absolutely appalling''. Another advocate viewed the document as "dripping in transphobia".
The leaked document stated that by agreeing to support the Statement of Special Character, students needed to adhere to practices according to their biological sex, and staff needed to ensure the practices were maintained.
This included using specific pronouns such as his or her, and if a student wished to use a name at school other than their legal name, "it must be a name that the college reasonably considers aligns with their biological sex".
It also included the separate use of male or female toilet facilities or single cubicles, separate male and female accommodation, wearing male and female uniforms and associated uniform policies and regulations, and male and female sports teams.
On biological sex and gender identity, it said: "Through the embryonic and foetal stages of development to maturity, each of the estimated 37 trillion cells in the body receives either XX or XY chromosomes which help programme the human body to be biologically male and female."
It said "contemporary trends" were constantly changing and "need careful attention".
"Some young people are experiencing significant confusion about their gender."
The document went on to say that the long-term health consequences of introducing hormones of the opposite biological sex into a child's developing body were largely unknown.
"This raises a serious question that the administration of sex hormones in the case of gender-dysmorphic children has been carried out without adequate clinical trials and rigorous testing."
It stated that there were "well-documented" cases of transgender adults "regretting the puberty-blocking treatment they were given as a teenager".
The school's Statement of Character in the Deed of Integration said it was a caring and openly Christian school, all fields of study are permeated with a biblical perspective, and that "each child has been created in the image of God".
"God's good purpose for us include [sic] our personal and physical design as male or female."
The college board of trustees chairman Paul Shakes said the working document was created by Bethlehem College Ltd, the school's proprietor, which guided the assessment of the school's special character.
The school acknowledged "that questions around gender and identity are really difficult and sensitive for people".
"Our heart goes out to those experiencing them," Shakes said.
"Gender identity has been an intense recent focus in our society, and we've been wrestling with questions around how to provide the greatest level of care and protection possible for students experiencing these questions."
Shakes said it considered its beliefs and the "relevant research".
"We have to ask ourselves: Is it caring to affirm to children they're the opposite gender to their biological sex? Would this be providing the highest level of care and protection possible for our students?"
"We believe we find our true identity in God," he said of gender identity.
"We acknowledge that others have a different view of identity and we respect this, but we don't believe people get a 'randomly assigned' body at birth," Shakes said.
"We believe life has more design, meaning and purpose than that.
"So we're concerned it's not wise or kind to support children down a path of experimental hormonal and surgical medical interventions."
Shakes said the school "fully" accepted that not every family or student within the school community would align with all the school's beliefs.
"We believe God loves them and desires only the absolute best for them. We simply ask them to respect our beliefs, just as we respect theirs."
"We believe God's good purposes for us include our personal and physical design as male and female, and we believe that is, including from a scientific perspective, a perfectly reasonable belief to hold."
Shakes said the school took its duty to provide every child with the "greatest level of care and protection" seriously.
"We also have a duty and legal responsibility to maintain our special character as a Christian school."
But Tauranga pride advocate Gordy Lockhart said, in his opinion: "Essentially what I just read here was an apology for homophobia, yet continuing homophobia.
"They are saying this is our view, if you don't like that, don't come to our school. That is discrimination, that is segregation, homophobia all rolled into one. It's absolutely appalling, who is anybody to judge another for who they are - certainly in an educational environment," Lockhart said.
Associate Education Minister and Tauranga Labour list MP Jan Tinetti said: ''We need to take young people where they are at and make a safe and inclusive environment for them. I know that gender can be quite fluid...''
Tinetti said they need to support young people "to feel included and safe"... "with how they are identifying gender at a specific point in time".
"One of my roles as Associate Minister for Education with responsibility for rainbow youth is that we need to ensure schools are safe and inclusive environments - which is why when we [published] the guidelines around relationships and sexuality education, we have put out resources to support that [that] will help schools in their journey to become inclusive and safe environments."
Asked if she was concerned statements such as the school's could impact students, Tinetti replied: "That is something the Ministry of Education will be working through with the school."
"They have already indicated that they are working that through with the school. I want to leave it with them to have those conversations with them. But my expectations are all schools - including state-integrated schools - are safe and inclusive places for all of our students - very much including our rainbow students."
End Conversion Therapy co-founder and leader Shaneel Lal said in their view the document was "dripping with transphobia" and the college "does not understand the difference between sex and gender".
"The school explicitly rules out the existence of trans people and insists that gender should align with biological sex."