Eruera Hāmiora Tumutara, also known as Eru Hāmiora Pio, was probably born in 1859 or 1860 in the Te Whāiti district south-east of Murupara in the Bay of Plenty. He was the third child of Hāmiora Tumutara Te Tihi-o-te-whenua Pio of Ngāti Awa and Ngāti Tūwharetoa, a tohunga, writer and important informant for Pākehā ethnologists, especially Elsdon Best. His mother was Te Whakahoro, also known as Maria Taka or Takawhare Te Ākaurangi, of Ngāti Tūwharetoa and Ngāti Kahungunu. From the 1880s his father was most closely associated with Ngāi Tamaoki and Ngā Maihi, two Ngāti Awa hapū based near Te Teko; in later life Eru also associated himself with Ngā Maihi and lived at Te Teko. In the 1880s his family was Catholic, but his father later returned to the beliefs and practices of his role as tohunga. Eru Tumutara moved on from both religions, and joined the nascent Ringatū church founded by Te Kooti.
Almost nothing is recorded about him until the 1920s. By then he had married Maria Mahurea of Ngā Maihi. It is possible that he served in his own Ringatū community as a pirihimana, an office similar to a church warden that was often held by aspiring Ringatū ministers. Although Ringatū tohunga were first gazetted as ministers under the Marriage Act in 1915, Eru Tumutara did not feature on the annual lists until 1923. The ritual of the Ringatū church was taken mainly from the Bible, especially from the Old Testament, and aspiring and practising Ringatū ministers learned long passages by heart. Eru Tumutara was later regarded as an expert in biblical scripture.
By the 1920s the church had become divided. Although Te Kooti had appointed various poutikanga (main pillars) as the leaders of the geographic sections of the church, he had not designated anyone to head the whole church after his death. The various prophets who proclaimed themselves leader were never accepted by all who called themselves Ringatū, and their beliefs and practices differed widely. Eru Tumutara was one of the leaders in the 1920s competing to unite the Ringatū church institutionally: to register it, and regulate its membership and finances. His own aim was to bring it closer to the more obviously Christian churches in dogma and ritual. Other leaders, with different solutions to the church’s problems, included Robert Biddle (Rāpata Peene) and Koopu Erueti, secretary and president respectively of the general assembly of the church from the mid 1920s.
The Ringatū church had always been marked by the rise and fall of new prophets, including Rua Kēnana, Te Weretā and others. Tumutara and his party seem to have been provoked into organising change by the rise of various tohunga, including Wī Keepa Hākiaha, about 1923. Like many of the others, Hākiaha declared he was the child Te Kooti had prophesied would carry on his work. He and his followers moved to Whakatāne, where Hākiaha seemed to be attempting to take over the Ringatū church and its main centre at Te Wainui in the Ōhiwa Harbour.
Tumutara and Biddle resisted Wī Keepa Hākiaha’s mission: their main complaint was that Hākiaha was turning Ringatū supporters away from the Bible, especially from the teachings of Christ. They also feared that the church’s base at Te Wainui and its funds might fall into the hands of prophets such as Hākiaha. At a general assembly of the church in 1924, Tumutara’s faction succeeded in getting him elected head of the Ringatū church with the title of bishop: he remained a registered minister until his death. As bishop he attended a meeting at Te Poroporo, Whakatāne, on 12 December 1925, where he baptised 50 people and consecrated two new ministers. This attempt to institute centralised control seems to have provoked further division and a massive withdrawal of support from Tumutara's section of the church.
In 1928 a general assembly of the church, now dominated by Erueti and Biddle, drew up a formal constitution and the church was registered under the Incorporated Societies Act 1908 in November 1929. The constitution called the head of the church the ‘president’, and Tumutara was sometimes mistakenly referred to by this title. It also established a register of bona fide members, which included the owners of the 600 acres granted to Te Kooti at Te Wainui. This move was designed to protect the established church and its property.
The terms ‘president’ and ‘bishop’ were not favoured by Te Raumoa Balneavis, private secretary to the native minister: he argued that they were not Māori, were not the names chosen by Te Kooti and were a cause of division. He advised Tumutara to do away with such titles and suggested alternatives. Tumutara found these names, including tumuaki (leader) for himself, unsuitable: tumuaki was sometimes used for Christ and he would not presume to use it, and the other suggestions were Kingitanga or Hauhau terms. He insisted that the Ringatū church was Christian and he would continue to be known as a bishop.
Tumutara was ecumenical in spirit and happily shared significant occasions with ministers from other churches. In 1928 he conducted the rites at the unveiling of the memorial for the Tūhoe elder Te Pouwhare Te Roau of Rūātoki, and then handed the event over to the Anglican Māori bishop, Frederick Bennett, and to Sir Apirana Ngata. Eru Tumutara taught that the Ringatū church was an offshoot of the Anglican church; he himself revised the Ringatū ritual to bring it nearer to the Christian model.
Eru Tumutara died at Te Teko on 11 January 1930, survived by his wife and five children. Mānihera Tūmātahi, an Anglican minister stationed at Te Ngae, who seemed to have a special friendship with the Ringatū bishop, wrote a moving farewell to him in the Anglican Māori paper Te Toa Takitini. Tumatahi lamented that if Eru had lived longer, the Ringatū and Anglican churches would have become even closer; he closed with Eru's favourite ecumenical saying, ‘tātau, tātau’ (all of us together).