A Presbyterian minister counts himself lucky to have taught hundreds of people about the history of their various churches.

The Rev Dr Allan Davidson, who retired this year after 27 years' lecturing at St Johns Theological College in Auckland, has been made an Officer of the New Zealand Order of Merit.

"I was fortunate to be appointed at a time of the churches breaking down the barriers of the previous generations and being open to working together," he said.

The Anglican institution had opened to Methodists, and soon came Baptists and Catholics.

"It meant we were not only involved in preparing vicars and clergy but also lay people who were interested in the study of the history of theology," Dr Davidson said.

"I firmly believe that if we don't know where we have come from, we don't understand ourselves in the present.

"It is an opportunity to recognise both the things which we can celebrate and the things we can recognise as our shadow side ... things that have been done in the name of christianity that we don't feel so comfortable about."

Dr Davidson, who was born in Hokitika, won scholarships for post-graduate and doctoral study in Chicago and Aberdeen.

After serving as a minister in Christchurch, he was encouraged to teach history following a spell relieving at Knox Theological College in Dunedin.

He accepted "as an adventure" a lecturer's job at Rarongo Theological College in Papua New Guinea and stayed nearly five years, with his wife Margaret and two daughters.

"I was exposed to a variety of languages and cultures and it was a richly rewarding and challenging time," Dr Davidson said.

At St Johns, his passion for research resulted in the publication in 1991 of his book Christianity in Aotearoa: A History of Church and Society in New Zealand.

It included major and minor religious faiths and is the Ministry of Education's text-book on church history.

In retirement, Dr Davidson supervises post-graduate students and is editing a history of the Anglican Diocese of Auckland.