"…because you are lukewarm, and neither cold nor hot, I will spew you out of my mouth." (Rev 3.16)
I was actually planning on writing a post about something completely different, when I decided to use this verse at the beginning. It is frequently cited as a warning against taking a moderate position, and at first glance, that might seem to be a reasonable interpretation.
But something about it didn't quite sit right. If, for example, being "hot" is good, wouldn't being "lukewarm" be better than being cold? So I decided to do a little research.
In my own library, I found very little dealing with this verse. The Book of Revelation is my least favourite biblical text, so this isn't terribly surprising (in that I don't have any books that deal with it exclusively). But even the New Jerome Bible Commentary passed over this verse without comment.
David Aune's note on the verse in the HarperCollins Study Bible says, "Cold, hot, and lukewarm are figures of speech meaning 'against me,' 'for me,' and 'indifferent'; lukewarm may also allude to the tepid and nauseous local water supply." (2314, n.3.15-16).
This didn't really answer my question: why would being "indifferent" be worse than being "against me"?
So I turned to the HarperCollins Bible Commentary. The commentary on Revelation, also written by Aune, notes that the community to which this part of the text is addressed, Laodicea, "was the most important city in the Lycus valley, where two other cities also contained communities, Hierapolis and Colossae (Col. 4:13)" (1193). Aune writes,
The community [in Laodicea] is condemned for being neither cold nor hot, but lukewarm..., a metaphor linked to the region's water supply. The "hot" springs of Hierapolis were famous for their medicinal properties, and the "cold" waters of Colossae were prized for their purity. The tepid waters of Laodicea, however, were both abundant and bad. (1193)
The fact that John counsels them to obtain "white garments" (of purity) and "salve to anoint your eyes so that you may see," might support this interpretation (cf. Aune 1193). I don't know, that part might be a bit of a stretch. It's difficult to know how this would have been interpreted by people in that community at the time.
Anyway, I thought that was interesting.