If the church is the glass and the water is the message, Bonhoeffer would not like what is happening in the emergent church in regards to preaching:
Anyone who is thirsty will drink water from any utensil, even if it is somewhat inconvenient. And it is better to take some trouble in getting the water pure than to drink polluted water out of a glass. (A Testament to Freedom, 151.)
The emergent church is attempting to make the church inviting for anyone by preaching non-threatening messages. By saying that their message is just part of a conversation, and that they don’t actually have the truth (Listening to the beliefs of emerging churches, 179.), they are presenting polluted water in a clean glass.
More to come on Bonhoeffer as I finish the first draft of my paper.