It's not that Butler, 73, was born a humanist; he was a cradle Catholic for more than 60 years before becoming a humanist three years ago.
He doesn't adhere to the excesses of Abrahamic religions - he lists misogyny, women not having power over their own bodies, difficulties with people who leave their faith, difficulties with different sexualities.
"These are things that my students who are dechurched would not appreciate."
Butler talks of the tenderness he sees in children with regard to the care of animals yet the world's major religions go in for the sacrifice of human or animal flesh.
A basic tenet of humanism is to look after one another - do unto others as they would do to you. Humanists seek to never do anything that would hurt anybody in any way or hurt a sentient being, he says.
The 2018 Census found 48.2 per cent of New Zealanders had no religion, compared with 41.9 per cent in 2013, 34.6 in 2006, and 29.6 in 2001.
Church is on the decline, Butler says.
"No sane child now would buy the idea that a man born of the Virgin Mary, crucified himself to himself, and is then taken up into heaven and that his mother one day also shot off to heaven."
As a teacher of intermediate-aged children, he noticed most of his students were not religious. "That is not to say they were not good."
Children not born into religion look at its beliefs with fresh eyes.
"If you're born into a religion it's very hard to leave but if you are not born into religion it's harder to join because you'd ask the obvious questions of the Christian narrative: could a man be born of a virgin, where's the sense of Jesus sacrificing himself to himself, why do the dates for the death of Christ differ in the Bible, why is there so much suffering when God can stop it?"
While Christianity does do a lot of good, Butler says a lot of people go through life as non-analysing Christians.
Religion is Stone Age and Iron Age beliefs not compatible with the 21st century, while humanism depends on rationalism, science and logic, he says.
Religion was humankind's first attempt to provide explanations for what was happening around them. When there was a tsunami or a volcanic eruption, people would attribute it to God being angry. This was okay for the time, but now science gives explanations for these events.
Democracy, prosperity, education, and social services make people independent of the financial shackles of religion and lead to independence of mind, he says. People living in developed nations are more likely to think independently.
He would like humanism to be taught in schools. Plus, religion needs to be studied as a subject so children can make choices about the most important things in life.
As well as establishing a branch, Butler hopes to start a public programme of speakers exploring who we are, where we are going, how to connect with the environment, how to bring up children, and what the best society for us is.
Butler says he doesn't know what happens after this life but if this is the only life it is better to make the best of it, live every moment with meaningful things, and when we make a mess make it right. Christians see life as a dress rehearsal for the afterlife.
Butler describes himself as "Indian by birth, Anglo-Indian by memory, Australian by nationality and New Zealand by temporality."
He was born in Delhi and educated in Kolkata, starting his teaching career there.
For more information email keithstclairbutler@gmail.com or search PalmyHumanists on Facebook.
