Exegesis:
oudeis oiketēs dunatai dusi kuriois douleuein ‘no slave can serve two masters.’ For douleuō cf. on 15.29.
oiketēs ‘slave,’ added in order to make clear that the reference is not to serving in general but to a slave’s serving.
ē gar ton hena misēsei kai ton heteron agapēsei ‘for either he will hate the one and love the other.’ miseō and agapaō are used here in the meaning ‘reject strongly’ and ‘prefer strongly.’ The future tense of both verbs expresses that this is what may be naturally expected.
ē henos anthexetai kai tou heterou kataphronēsei ‘or he will be devoted to the one and despise the other.’ antechomai and kataphroneō are as strong as agapaō and miseō.
antechō ‘to cling to,’ ‘to be devoted to.’
kataphroneō ‘to despise,’ ‘to treat with contempt.’
ou dunasthe theō douleuein kai mamōna ‘you cannot serve God and money,’ personal application of what hitherto was stated in general terms. mamōnas is represented here as a power which may lay hold of people.
Translation:
No servant can serve two masters is redundant in that the relationship between the participants is indicated thrice, in “servant”, or ‘slave,’ in “serve”, or ‘be the slave of,’ and in “master”, or ‘owner.’ Less redundant renderings may be more idiomatic, e.g. ‘no slave can have two masters, or, can have-as-master two men’ (Bahasa Indonesia), ‘no one can be the slave of two masters,’ ‘there is no slave who can hold two servitudes, or, can make himself slave of two men’ (Javanese, Tae’). For ‘slave’ see 7.2.
For hate see on 1.71; for love on 6.27.
He will be devoted to the one and despise the other, using verbs that are approximately synonymous with the preceding ones, but in reversed word order, a well known stylistic device in Greek, but unacceptable in some receptor languages, which prefer parallel order. To be devoted to has also been rendered by “to be attached/loyal to” (Translator’s New Testament, Good News Translation, cf. Phillips), ‘to make-common-cause-with’ (Batak Toba), ‘hold strongly to the side of’ (Sranan Tongo), and to despise by ‘to make-light-of’ (Bahasa Indonesia), ‘to neglect’ (Balinese), ‘to be indifferent to,’ ‘not to count’ (Sranan Tongo).
You cannot serve God and mammon. Although the verb is preferably to be rendered as in the first occurrence, differentiation may be required, e.g. because here ‘God’ is one of the objects; hence, ‘have-as-lord’ (Bahasa Indonesia), ‘worship’ (Balinese); or because it is used metaphorically here, hence e.g. “serve” instead of “be the slave of” (New English Bible). Where no verb is available that fits both objects an appropriate synonym may have to be inserted, e.g. ‘to worship God and be a slave of Riches/Wealth/Property/Money.’ Mammon functions here as a person. If possible one should keep to the noun used in vv. 9, 11 (see above), marking it as a proper name. Where such personification is idiomatically unacceptable, it may be possible to use the name of the god of wealth (as in an older Balinese version); or one may transliterate the Greek word (cf. The Four Gospels – a New Translation‘s “Mammon” here, “world” in vv. 9, 11), where necessary adding a footnote that equates the translation in vv. 9 and 11 with this transliteration. Or, again, one may shift to a non-personifying rendering, where necessary adjusting the verb, cf. e.g. ‘strive-after-property’ (Toraja-Sa’dan), ‘be devoted to … riches’ (Javanese).
Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.