The Greek that is translated as “one” in English in these verses (John 10:30, 17:11, 17:21, 17:22, and 17:23) is translated in Kikuyu as ũmwe or “one singular entity.” This translation required a complex theological interpretation in relation to the nature of the trinity and the unity of Jesus and his disciples. The translators determined that both the unity of the Father and Jesus is that of “one person” or “the same” as well the unity between Jesus and his followers (and the followers to each other).
A.R. Barlow (in The Bible Translator 1952, p. 29ff. ) explains:
“‘One’ in Kikuyu is expressed by the stem -mwe combined with a prefix appropriate to the noun it qualifies (when used as an adjective) or represents (when used as a pronoun). As in all Bantu languages, nouns fall into groups or classes, each of which, generally speaking, has its distinctive prefix. Thus with the word for ‘shoe’ (kiratu) –mwe becomes kĩmwe (kĩratũ kĩmwe ‘one shoe’); with the word for ‘man,’ ‘person,’ ‘being’ (mũndũ) it becomes ũmwe (mũndũ ũmwe “one person”). Singular and plural are likewise distinguished by change of prefix, and a singular noun necessitates the use of a singular prefix with its associated adjective or pronoun, whereas a plural noun requires its adjective or pronoun to take a plural prefix.
“In common with other adjective-pronouns –mwe assumes plural as well as singular forms. When used with a plural noun it conveys one of three meanings: (a) ‘one lot (set. kind, family, fraternity, group, etc.),’ (b) ‘the same,’ or (c) ‘some.’ The form appropriate to persons, men, beings (andũ) is amwe.
“So in translating ‘one’ in any of the above passages in St. John’s Gospel we have to choose between ũmwe (sing.) and amwe (pl.).
“The choice involves questions as to the nature of the Trinity and the character of the unity which being ‘in Christ’ imparts to His followers, both in relation to Himself and to one another. This is a case in which the translator cannot avoid theological issues.
“In John 10:30 (‘I and my Father are one’) by using ũmwe we are stating ‘I and my Father are one (person, entity)’ or ‘the same.’ Grammatically the use of ũmwe (sing.) is wrong; ‘I and my Father’ should strictly be followed by the plural amwe. But the use of amwe (‘one lot’) would denote a mere family or sectional relationship.
In John 17:11 and 17:22 (‘so that they may be one, as we are one’) also, grammar demands amwe (in both occurrences of ‘one’). But this would again limit the desired degree of unity to that of membership in a family or other (more or less) close association: ‘that they may be united (associated, belong to the same fraternity), even as we are united (etc.).’ If a deeper, more mystical union is to be indicated we are thrown back on ũmwe: ‘that they may be one person (one entity), even as we are one person (one entity).’ Or are we to differentiate between the disciples and the Divine Persons and use amwe for the former and ũmwe for the latter?
“In all these passages the existing Kikuyu New Testament has ũmwe, whether the reference is to the disciples or to Christ and the Father. As far as I am aware this has never been criticized by our African Christians, although in 17:11, 21, and 22 its use in ‘that they (all) may be one’ might even convey the sense ‘that they (all) may be reduced to one,’ i.e. to a single individual!”
Note: All three currently (2022) available Kikuyu Bible translations (Ibuku Rĩrĩa Itheru Rĩa Ngai; Kiugo Gĩtheru Kĩa Ngai, Kĩrĩkanĩro Kĩrĩa Gĩkũrũ Na Kĩrĩa Kĩerũ; and Kĩrĩkanĩro Gĩa Gĩkũyũ) still only use ũmwe in all of the above instances.
See also this lectionary in The Christian Century .