We found our visit to Christ Church Cathedral in Stone Town, Zanzibar, deeply moving, for it sits on the site of what was formerly the largest slave market in East Africa. The designers of this cathedral wanted to show through a physical symbol how the gospel breaks the chains of slavery. No longer would the location be a place of evil deeds and horrible atrocities, but of God’s embodied grace.

Those who built the cathedral wanted to express how Jesus’s death on the cross provides freedom from sin—that which the apostle Paul speaks of in his letter to the church at…