So, because you are lukewarm, and neither hot nor cold, I will spit you out of my mouth. (Revelation 3:16 ESV)
FanaticFanatic
Lukewarm is a strange word. Modern English has lost the word, “Luke” from usage, but it used to mean tepid. Like your breakfast oatmeal, if you let it cool down from hot… but before it reaches cool.
Farm animals were declared dead when their flesh and blood were determined to be luke. Cleaning water was luke when it was not warm enough to be useful. A hearth was considered safe to leave unsupervised when it became luke.
Adding the adjective warm to the root word luke exaggerates the tepidness. The word could have evolved as lukeluke, or warmwarm… but probably artistic concerns led folk to start to use lukewarm to define something that is an extreme of worthlessness.
The other ends of the spiritual spectrum are necessarily extreme. Rejecting Christ (the coldness of atheism) has eternal consequences. That rejection is not a casual, thoughtless thing. Because the Grace of Christ is too big to be rejected casually.
Following Christ (the heat of knowing Him) has eternal consequences, too. That decision, necessary for eternal survival, is not a casual, thoughtless thing.
In fact, in the light of all that the gospel promises and provides, rejecting it could be declared foolishfoolish. And union with Christ could be called fantasticfantastic.
Which pulls us into being fanaticfanatics.