Contextualization means taking the universal, unchanging gospel of Christ and translating it into an ever-changing, sin-filled culture. On one side of this equation, contextualization requires that we know and obey the Scriptures lest we lose the truth of our message in transaltion. On the other hand, we must also be students of culture who can "know the times" and discern how best to proclaim the good news in a way that makes sense to the people to whom we've been sent.
Contextualization is neither safe nor easy. In an attempt to share the gospel in culture, some have gone too far; using language and methodology so familiar to the culture that it isn't discernible as being meaningfully different from what was already there (the theological term for this extreme is syncretism). Others take things too far in the other direction and fail to contextualize enough. This leads to an obscured message that requires the listener to leave his culture to hear the gospel at all.
Despite the dangers and difficulties of contextualization, we have no choice but to commit to it. As the good news came to us, so it must also go through us. In order to make disciples– in order to be disciples– we must constantly wrestle with how the gospel respects, rejects, and redeems our cultures.