Missionaries to the Australian colonies faced frequent charges that their efforts were beyond the mental capabilities of their flocks. Such threats could even come from the clergy. After early failures to persuade Aboriginal children to remain in his household, Samuel Marsden (1764-1838), the colonial chaplain to New South Wales who was instrumental in bringing the gospel to Maori in Aotearoa New Zealand, doubted that Aborigines were capable of civilized or Christian responses and was increasingly reluctant to extend limited funds to missionary efforts in New South Wales.^[9] Responding to a request from his archdeacon for information on the state of New South Wales Aborigines in 1826, Marsden (1974:349) admitted their essential humanity but questioned their capacity for religious thought: 'the want of reflection upon their past, present and future, which is so strikingly apparent in the whole of the conduct of the Aborigines, opposes in my mind the strongest barrier to the work of a Missionary'.

This passage must be considered in the context of the debate then running between Marsden and his enthusiastic subordinate, Lancelot Threlkeld (1788-1859) of the London Missionary Society, who was dependent on Marsden for maintaining funds to his mission to the Awabakal people of Lake Macquarie. Threlkeld's description of his intermittent congregation was written in the same year as Marsden's comments, amid considerable settler hostility towards Aborigines and with the fear that the mission was at risk of losing its funding. While acknowledging that the religious ideas of his flock were false, Threlkeld (1974, I:52) found them no more 'contemptible than the pretended finding of the golden-plates and the magic spectacles, through which alone the book of Mormon could be read by the impostor Joe Smith'. Threlkeld held that the beliefs of his congregation indicated their religious sensibility and he made close analogies between Jewish, Christian, and Awabakal rituals that can be read both as a plea for universal ability and an implicit claim for continued support of the mission. The point also had legal implications: on the basis that Aborigines did not believe in a 'Supreme Being' and therefore could not swear an oath, Aboriginal testimony was inadmissible in the law courts of New South Wales until 1876 (Wright 2001:140). Against numerous detractors, Threlkeld insisted:

Ultimately, Threlkeld's arguments for the mission failed and it was closed in 1828. He believed that the principal reason the funding was stopped was because he disputed the common belief that 'Aborigines are incapable of civilization and instruction' and he acknowledged that on this point he was in opposition to Marsden. Against many settlers, significant sectors of the colonial administration, and even his own superior, Threlkeld (1828:65) argued that 'Aborigines are not "Baboons", that they have no "innate deficiency of intellect''', and that they might be brought eventually to 'sit at the feet of Jesus, clothed in their right mind'. He was aware that evidence of the religious sensibility of Aborigines strengthened their claims for political, legal, and economic rights. For this reason, he was strategic in his choice of terms. Along with many other missionaries, Threlkeld used 'Gentile' rather than 'heathen' to describe his congregations. 'Gentile' sidestepped the Christian/heathen, civilized/savage oppositions and drew Aboriginal people closer to Biblical history where belief in the Jewish God was an ongoing matter of theological debate and discussion rather than a scientific, moral, or intellectual sign of human difference and ability.

During the first half of the nineteenth century, the most important British theorist to draw on reported observations of newly-encountered people was James Cowles Prichard (1786-1848), described by his counterpart in the second half of the century, Edward Burnett Tylor, as the 'founder of modern anthropology' (Stocking 1973:x). Prichard's use of physical evidence might have left him vulnerable to Watson's invective against those who 'measure mind by the rule and compasses' but he remained true to his devout Quaker upbringing and later membership of the Evangelical wing of the established church and maintained his belief in the orthodox view that humankind was born of a single origin.^[10] Prichard's major ethnological publication, Researches into the Physical History of Man(kind), was revised three times between 1813 and 1847. The first volume of the third edition includes a new chapter that marks a significant shift from the physical focus of his earlier work. Titled 'the psychological comparison of human races', the chapter is based almost entirely on Moravian missionary accounts of Bushmen, Eskimos, and sub-Saharan Africans.^[11] Prichard readily accepted Moravian conversion accounts as psychological evidence that all people share the 'same mental endowments, similar natural prejudices and impressions, the same consciousness, sentiments, sympathies, propensities, in short, a common psychical nature or a common mind'. The evidence for religious and by extension moral and intellectual parity could be found in the common 'tendencies to superstitious belief, as well as the same moral impressions as the rest of the human family'. Prichard believed he had defined a 'new subject of enquiry'.^[12] His modern editor George Stocking, Jr. (1973:lxxxiv) argued that Prichard had extended the human unity discussion from the physical to the psychological realm, a position developed in the second part of the nineteenth century as the 'psychic unity of man'. Evangelical Christians of the period who were familiar with the text, however, almost certainly viewed Prichard's use of missionary texts as an important scientific confirmation of the general unity of the human species, viewed in Christian terms and confirmed by missionary observations.

Debates on the unity or otherwise of the human species were influenced by political events and often coalesced around societies and institutions.^[13] The year after Prichard published the first volume of his third edition, the Aborigines Protection Society was established in Britain to agitate for indigenous rights. While the fight for legislation against slavery in the colonies had been won in 1833, Evangelical Christians were increasingly concerned by the more insidious dangers of colonization. In 1838, the Anglican Church Missionary Society petitioned the British Parliament against the granting of a major charter to colonize New Zealand, arguing that European colonization had 'disastrous consequences to the Aborigines of uncivilised countries in their rights, their persons, their property and moral condition' (Stenhouse 1994:399). However, there was no single missionary stance on colonialism in the Pacific throughout the nineteenth century. Denominational differences, political circumstances, both internal and international, as well as changing ideas of the relationship between subject and state meant that missionaries occupied the spectrum of political responses to colonization and often advocated European intervention, particularly in the face of settler encroachment on indigenous land.^[14]

During the early nineteenth century, many missionaries proceeded to the field on the assumption that humanity could be defined by the capacity to form a relationship with the Christian God. Once in the field, and particularly when they began to translate the Scriptures into local languages, missionaries became profoundly entangled in indigenous beliefs as they searched for concepts that could bridge the differences between Christian doctrine and cosmology on the one hand and local ideas on the other.^[15] Evidence for human unity and God's immanence could be found in a variety of sources. The Protestant call to translate the Bible into all tongues was based on the belief that every language had been created by God and therefore contained the means to describe the revelation of Jesus (Sanneh 1989:201). In 1850, John Geddie (1815-1872), a Presbyterian missionary on the island of Aneityum in what is now Vanuatu, wrote of translating the New Testament (1975:63): 'The study, however, is one of intense interest and delight; and those are privileged indeed, whom God permits to prepare the key which will unlock the hidden treasure of divine truth, which makes the soul rich for all eternity'. While the presence of heathen spirits or gods was generally taken by missionaries as evidence of degeneration, it could also serve the more significant purpose of proving the essentially spiritual nature of the unconverted. Geddie's colleague John Inglis (1808-1891) insisted that the Aneityumese idea of spirit possession indicated a spiritual — as opposed to secular — nature that corresponded closely to the Christian idea of the spirit and revelation. As with Threlkeld, Inglis made ready analogies between local and Jewish beliefs. He believed that Aneityumese messages from the spirits were:

Such analogies served the dual purpose of bringing the heathen into the Christian world and indicating to sceptics that they shared their history and humanity with the frequently despised native. For many missionaries, conversion was not merely proof of the indwelling God but was a significant marker of their own faith for it proved the universal appeal of Christ and, by extension, the unity of humankind.