The message is not really theirs. The missionaries did not originate it. They were not there when it was first given, nor are they a member of the culture in which the message was communicated. They know that they must be diligent to present themselves —
Study and do your best to present yourself to God approved, a workman [tested by trial] who has no reason to be ashamed, accurately handling and skillfully teaching the word of truth. – 2 Timothy 2:15
In relationship to the biblical message, the missionary is simply a messenger, an ambassador – a secondary, never a primary source.
First, they want to communicate Christ in such a way that the people will understand, repent and believe the gospel. Second, they want to commit the message —
The things [the doctrine, the precepts, the admonitions, the sum of my ministry] which you have heard me teach [a]in the presence of many witnesses, entrust [as a treasure] to reliable and faithful men who will also be capable and qualified to teach others. – 2 Timothy 2:2
— commit the message in culturally relevant terms that only indigenous leaders can fully understand.
Michael Frost gives an example of preaching the Gospel to the Zanaki people of Zimbabwe using Revelation 3:20 as the text. 12 He explains that when we visit someone in British culture, their door will be closed and probably locked and the inhabitants safely and privately inside. You therefore have to ring the bell or knock loudly to gain entry. In Zanaki homes, however, there are no doors. If you visit a friend you simply call out loudly at the doorway. Your voice would be recognised and you’d be welcomed in. In that culture the only people who knock are thieves because they do not want to be identified! If, having knocked, they heard noises inside they’d disappear rapidly. Revelation 3:20 speaks of knocking and calling out, so a message contextualised to Zanaki culture might emphasise the calling out. Sadly the Victorian missionaries who first sought to evangelise this tribe emphasised the knocking and by doing so made Jesus out to be a thief!