The creation of a Centre for Cultural Witness at Lambeth Palace, to serve the Church of England within an ecumenical partnership that already stretches across Europe, offers an opportune time to reflect upon the place—even the meaning—of “culture” in witness of the church. The analysis presented here identifies three senses in which that term might be applied to witness: as that from which the witness comes, that through which it comes, and that to which it comes. At least in theory, a strong cultural emphasis might (or might not) be placed on each of these dimensions independently. However, while this may prove to be a useful distinction, it risks perpetuating an assumption that churches, and Christians, stand outside the culture of those they address, speaking as if from beyond it. In the second half of this paper, I work, instead, from the recognition that the Christian speaks from a position of a shared creaturehood, shared humanity, and—in myriad ways—a shared culture. Approached that way, the mission of the church can fruitfully be seen as witness to a theologically specific understanding of that which is shared. I conclude with the suggestion that this can be ably resourced from the broad tradition of a Platonic “Christian humanism”.