Revelation 3:14-22 (ESV)
14 “And to the angel of the church in Laodicea write: ‘The words of the Amen, the faithful and true witness, the beginning of God's creation.
15 “‘I know your works: you are neither cold nor hot. Would that you were either cold or hot! 16 So, because you are lukewarm, and neither hot nor cold, I will spit you out of my mouth. 17 For you say, I am rich, I have prospered, and I need nothing, not realizing that you are wretched, pitiable, poor, blind, and naked. 18 I counsel you to buy from me gold refined by fire, so that you may be rich, and white garments so that you may clothe yourself and the shame of your nakedness may not be seen, and salve to anoint your eyes, so that you may see. 19 Those whom I love, I reprove and discipline, so be zealous and repent. 20 Behold, I stand at the door and knock. If anyone hears my voice and opens the door, I will come in to him and eat with him, and he with me. 21 The one who conquers, I will grant him to sit with me on my throne, as I also conquered and sat down with my Father on his throne. 22 He who has an ear, let him hear what the Spirit says to the churches.’”
What does Jesus mean by "lukewarm"? From the context it is clear that it refers to a middle state between two extremes (hot and cold), but this begs the question: what is meant by "hot" and "cold"?