"How can they hear?" might be the most appropriate question related to contextualizing gospel communication. Those who would respond to the gospel must have some basic understanding of what they are being asked to consider. Understanding something of the environment in which the original action took place and how the gospel impacts the conditions of their own setting is essential for a person to respond to the gospel message. It is not what the gospel means to them, but what the gospel means for them, as it is the objective, real work of the Son of God. This is something that Paul understood clearly. When the Apostle stated his willingness to become "like" a Gentile, express weakness or much more, the purpose was so that his hearers could grasp the implications of the gospel where and "when" they were.
I have said it many times, but it always seems to bear repeating-- contextualization is not watering down the message. In fact, it is exactly the opposite. To contextualize the gospel means removing cultural and linguistic impediments to the gospel presentation so that only the offense of the cross remains. It is not removing the offensive parts of the gospel; it is using the appropriate means in each culture to clarify exactly who Jesus was, what He did, why He did it, and the implications that flow from it. Oftentimes, it is unclear communication (and a lack of contextualization) that contributes to some rejecting something they do not understand. If the feet of those who bring the gospel are beautiful upon the hills, it is at least partly due to the fact that those who hear the gospel understand and appreciate its life transforming truth. This often occurs through critical contextualization.
Christan contextualization has to include and understanding of the work of Jesus, in His incarnation, life and teaching. Incarnated as a first century, Palestinian Jew, Jesus was so thoroughly a part of His culture than, when being betrayed by Judas, He had to be identified by a kiss. He didn't levitate above the earth or have a perpetual light emanating from Him. He came to earth fully man. He ate the same foods as the disciples, walked the same roads, grew tired, slept and prayed. His teaching consisted of familiar to the people in his context: farmers, widows, fields, crops, money and heaven. Jesus didn't merely bring heaven to earth; He taught about it in earth's terms from a very specific cultural environment.
Paul followed this method. Whether Athenian philosophers, the libation or heathen poets, he used culturally familiar and appropriate markers as bridges to cross, communicating and clarifying the gospel's truth. Being weak meant that he humbled himself to bring the gospel to those society viewed as weak. To the strong, he presented his credentials of apostleship to garner a hearing. Before Jews, he refrained from legally offensive behavior. Before Gentiles, he exercised his freedom in Christ. In whatever situation he found himself, he used whatever way possible to bring and communicate a clear gospel to as many as possible, even if only a few responded. He did not allow context to become a barrier to the gospel; he even used cultural cues as a bridge for effective gospel communication.
So, contextualization matters because clear gospel communication matters. Feel free to weigh in with your thoughts in the comments.
If you are interested in more, here is a lengthy series I did on the issue of contextualization.