Just as Christ identified with people so too everyone and especially missionaries need to listen, understand, identify and feel for the people they wish to reach before they can effectively communicate. Communicating is not so much what is said as what is understood.
The credibility of the messenger and his or her understanding of their culture is also important. But even this is not enough if the messenger does not understand his own culture. Transferring ones own culture rather than the pure Biblical Gospel is another common consequence of not learning and studying culture and communications.
Bringing the Gospel to an unreached people group is not easy, it is as difficult as brain surgery. Therefore it should involve just as much preparation and ongoing learning. Learning from past history and willing to try new methods.