So, because you are lukewarm and neither cold nor hot, I will spit you out of my mouth... Revelation 3:16
This verse is often interpreted as a warning to keep the heat turned up on performing in order to be accepted by God. The proponents of this interpretation tend to point out marginal efforts made by those professing Christ as proof of humanity's death knell. That line of thinking leads to a logical conclusion. If 'hot' is good then 'cold' is bad.
But the verse says ‘lukewarm' is bad, which leaves cold being just as desirable as hot. Well then, what's the point of keeping the embers burning if the same status is awarded when putting forth no effort?
Probably a good time to mine an interpretation that makes more sense when viewed through the Cross of Christ.
When was humanity's salvation and righteousness contingent on works? Before the cross. So...since the Cross, what is humanity's salvation, redemption, and righteousness contingent on? His work.
This verse is addressing their failure to trust in the sufficiency of the cross for salvation, redemption, and righteousness. These folks were propping up the gospel with their works and using financial success as their proof. We know that from the next verse.
17: You say, ‘I am rich; I have acquired wealth and do not need a thing.’ But you do not realize that you are wretched, pitiful, poor, blind and naked.
18: I counsel you to buy from me gold refined in the fire, so you can become rich; and white clothes to wear, so you can cover your shameful nakedness; and salve to put on your eyes, so you can see.
How do we buy what Jesus accomplished? The point is, we can’t! That was the purpose of the law all along. (Check out Romans 3:19-28) The word translated 'buy' infers to be in the market for, so the folks of Laodicea - and anyone else struggling to divorce themselves from the idea that salvation is a mixture of pre-cross effort and post-cross grace - are being instructed to remember that what Jesus accomplished is impossible for them to purchase.
Live as a disciple of Moses or Christ but don't mix the two. You either understand that Jesus accomplished the impossible or you don't. Mixing the two gets you wretched, pitiful, poor, blind and naked. Don’t settle for that. The cross changed everything!