...The cold water symbolized the unbeliever, and the hot water symbolized a believer who was executing the Spiritual Life.
'So because you are lukewarm, and neither hot nor cold, I am about to vomit you out from My mouth. (
Revelation 3:16)
The Christians at Laodicea are called lukewarm, i.e. neither hot nor cold. Notice the reversal of the sequence from "cold nor hot" (verse 15) to "hot nor cold" (verse 16). This represents the beginning and end of a sequence. There are Spiritual solutions for cold or hot. Cold people can be evangelized, and hot ones can metabolize Bible Doctrine.
However, lukewarm believers are carnal. The have sinned, lost the Filling of the Holy Spirit, and neglected to Rebound. If they refuse to Rebound, there will be no solution for them. Their end will be the sin that ends in death, which is described as being vomited out of the Lord's mouth...
http://www.biblenews1.com/firetest/firetestb.htm