Matthew Cowley was born on 2 August 1897 in Preston, Idaho, USA, the son of Matthias Foss Cowley and his wife, Abbie Hyde. The family moved to Salt Lake City when Matthias was appointed an Apostle, a member of the Council of the Twelve which ruled the Church of Jesus Christ of Latter-day Saints; he was disfellowshipped for taking a second wife after the church had officially abandoned the practice. Matt nevertheless had a careful Mormon upbringing, and attended the Latter-day Saints University in Salt Lake City. Before completing his education he was called in 1914 to go on a three-year mission; he wanted to follow his eldest brother to Hawaii, but was instead sent to New Zealand.
Cowley arrived in Auckland on 23 November 1914 and was assigned to the Hauraki district. The mission focused on Māori and Cowley had to learn the language quickly. He did so with passion and skill, and within 12 weeks knew waiata and haka and began preaching and writing his diaries in Māori. His mission was extended for two years in 1917. By the time of his release from his mission on 9 May 1919 he had been president of the Ngāpuhi district, president of the Mormon Sunday-school body, and a special assistant to the president. His most remarkable achievement was a revision of the Māori text of The book of Mormon and the translation of two other key Mormon works, with the assistance of two Māori elders, Wi Duncan and Stuart Meha. The translations were remarkably adept for one new to the language.
Following his return to the United States, Cowley attended the George Washington University Law School in Washington DC. After graduating he worked part time for Senator Reed Smoot, then opened his own practice in Salt Lake City. He married Elva Eleanor Taylor there on 13 July 1922; they would have one daughter, Jewell.
Cowley's heart was partly in New Zealand and he maintained an extensive correspondence with Māori friends, keeping an eye on church policy towards New Zealand. In 1938 the church's president invited him to serve a three- or four-year term as president of the New Zealand mission. The term was lengthened in October 1940: he stayed behind when the 36 American elders serving under him returned home because of the war.
The church was now wholly Māori, but Cowley was well-suited to coping with this. His knowledge of the language and enjoyment of their hospitality inspired a warm regard among Māori, who called him Matiu Kauri. He attended and spoke at tangihanga and suggested the building of a carved Mormon house at Nūhaka. He involved himself in secular Māori issues, attending the Young Māori Conference in May 1939. Cowley and his wife first fostered and then adopted a young part-Māori boy, Anthony Ronald Hameora Bradley, whom they called Toni. Cowley's actions reflect not just a naïve enthusiasm for things Māori but also an ambition to nurture children who would grow up strong in the Mormon faith. He used exhortations and songs and the printed slogan 'Kia ngāwari' (be patient) to instil the faith. He was unable, in the absence of American lieutenants, to discipline or excommunicate Māori who ignored the standards of the Mormon Gospel; in any case, he preferred to use encouragement.
'My skin is white, but inside I am a native', Matthew Cowley once told a group of North American Indians. More comfortable than any other Mormon of his generation with people of non-European cultures, he was admired by non-Mormons, passionately loved by Māori and venerated after his death – even called the best Māori speaker in the land. He advocated that Māori Mormons continue to use 'their own beautiful language'. Yet he owed his status to the Latter-day Saints' distrust of Māori in leadership; although they were allowed in the 1930s to serve as district presidents, there were few able Māori with status in the sect.
After Cowley's departure from New Zealand in September 1945, the Mormon mission took a very different direction, ending the separate existence of the Auckland Māori branch, rejecting those Māori traditions regarded as inconsistent with Mormon values, and gradually suppressing the use of the Māori language and encouraging European members. Cowley was probably disappointed by this policy, although he perhaps accepted its necessity; he had himself cultivated European and government contacts, and had sought to improve Māori hygiene and to teach Māori people American decorum, music and dancing.
Soon after his return to Utah, Cowley gained the status of Apostle and member of the Council of the Twelve, and was the first (and only) president of all the Pacific missions. He played a crucial role in the decision to build a temple and a church college in New Zealand. He died suddenly on 13 December 1953 at Los Angeles. Natty in appearance, homely in temperament, his somewhat paternalistic benevolence allowed him to have an unusual impact among Māori.