What are some of the signs that a church is growing lukewarm, much like the Laodicean Church did?
Frog in a Pot
A church doesn’t become lukewarm overnight. It takes year after year for this to happen, but the tragic thing is, since it’s so slow and gradual, many churches don’t even notice it. It’s like the frog on the stove. The heat is slowly getting turned up, but it’s so slow, the frog doesn’t notice, so he doesn’t panic and jump out. Rather, not noticing the change, he’s eventually cooked. If the frog had been tossed into hot water in the beginning, he’d have quickly jumped out, but because it was slow but steady, the frog never noticed, and it lead to his death. The same thing can happen to churches and it happens without them even knowing it. Many churches have a routine where the opening prayer is followed by a song, then the collections or offerings is taken, then another song…and suddenly, it’s like getting dressed in the mourning. It’s so much of a routine that it loses its meaning. When we worship God and come before Him, it should be anything but just following a routine. It should be an experience where they can meet God. 
When Jesus addresses the Laodicean church, He doesn’t have much good to say about it. To begin with, He instructs the Apostle John to tell them, “I know your works: you are neither cold nor hot. Would that you were either cold or hot! So, because you are lukewarm, and neither hot nor cold, I will spit you out of my mouth” (Rev 3:15-16). The more accurate description would be that this church is so lukewarm that Jesus vomits them out of His mouth because they are neither hot (on fire for Christ) or cold (refreshing to those who thirst for God), but are in fact, lukewarm, and it leaves a bad taste in His mouth. Anyone who’s drank lukewarm coffee knows it’s not any good. It’s the same with a soft drink that’s gotten warm and grown flat. Let me say, that’s a serious rebuke from Jesus. Why are they so lukewarm? In short, it is their prosperity, “For you say, I am rich, I have prospered, and I need nothing, not realizing that you are wretched, pitiable, poor, blind, and naked” (Rev 3:17). Jesus’ counsel to them is 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” (Rev 3:18). They have possessions, but don’t realize, spiritually-speaking, they are blind, impoverished, and poor. Their solution is to buy gold that’s been refined by fire, meaning perhaps, they need to go through some persecution and trials because trials purify and strengthen our faith, however, they don’t want that. They want to sit in their pews and stew. They care only for themselves and their possessions. Little else matters to them, and that’s why they’re so lukewarm.
Discipline and Love
You cannot have love without discipline, and you cannot have discipline without love, so Jesus counsels the church, “Those whom I love, I reprove and discipline, so be zealous and repent” (Rev 3:19). He loves this church, even though they’re lukewarm, so Jesus reproves them by His Word and by His discipline, and that’s in order for them to recapture their first love…that zeal that they first had after they were saved, so He desires that they repent, and often discipline and reproof does that. It’s almost as if Jesus cannot get into this church, so He’s left standing outside the door. John writes, “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” (Rev 3:20). The point is, Jesus is not inside this church, but has been pushed aside or outside of the church, and now He stands at the door. He knocks so they’ll let Him enter, meaning He’s not inside this lukewarm church. When God disciplines, He never disciplines in anger. It’s always done in love, because if He didn’t care about us, He’d let us do what we want and that would end in disaster, so just as a parent disciplines their child because they love and care for them, it’s even more so for Jesus Christ Who rebukes those He loves and chastens every child of God (Heb 12:6-11).
Whoever Has Ears
Jesus often used the phrase, “Whoever has ears to hear, let him listen,” so this may mean we’re not listening to Christ or His Word, the Bible, thus He says to the church at Laodicea, “He who has an ear, let him hear what the Spirit says to the churches” (Rev 3:22). The point is, a lot of people listen, but they don’t really hear. Many people look but they don’t really see. You can hear something, but if you don’t act on it, do you really have “ears to hear?” Jesus marks the difference between hearing His words and doing them by saying, “Truly, truly, I say to you, whoever hears my word and believes him who sent me has eternal life. He does not come into judgment, but has passed from death to life” (John 5:24). In the Parable of the Sower, only the seed that have ears to hear and then wills to act actually believe in Jesus and grow and thrive. You can say you believe in Jesus, but if you don’t do what He commands, is that really belief? I can believe in seatbelts, but if I don’t put them on, I’m not listening to the authorities who command us to wear them. Hearing alone does nothing…it is those who do the will of God that can actually say they hear the Word of God and do them. Listening doesn’t guarantee doing, but hearing is different; when we hear, we act (at least we should). That’s what Jesus wants the Laodicean church to do. They must repent and turn back to their first love and do the kind of works they did when they were first saved. Leavening or yeast often represents sin in the Bible, and guess what…yeast or leavening works best in lukewarm water.
I believe the church needs revival. They need to repent and return to that zeal that the first century church had. They visited the sick, helped the poor, fed the hungry, went to the prisoners (Matt 25:35-36), and that was seen as doing it to Jesus (Matt 25:40), however, if they do nothing for Him, they are doing nothing to Him, and that’s one of the worst signs of an apostate or lukewarm church there is. In fact, it may reveal that they were never saved in the first place, and the consequences of that are unspeakable (Matt 25:41-45), and tragically, for some, “these will go away into eternal punishment, but the righteous into eternal life” (Matt 25:46).
Here is some related reading for you: What is Backsliding: Is it Biblical? 
Resource – Scripture quotations are from The Holy Bible, English Standard Version® (ESV®), Crossway Bibles. (2007). ESV: Study Bible : English standard version. Wheaton, Ill: Crossway Bibles. Used by permission. All rights reserved.