What does being lukewarm mean in contrast with being hot or cold for the church of Laodicea?

The best way to take this is the way it is written.

“To the angel of the church in Laodicea write:”

It was written to the angel of the church, not to the individual believer.

Rom 8:1 There is therefore now no condemnation to them which are in Christ Jesus, who walk not after the flesh, but after the Spirit.

Jhn 3:18 He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.

The description of the people does not sound like believers in Christ, but unbelievers who made a good portion of the membership.

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.

A true believer would never be described this way.

What does being lukewarm mean in contrast with being hot or cold for the church of Laodicea?

God welcomes those who are excited to come to him. God can correct those who are hostile to him. However, those who are disinterested in him are those that little can be done with.

Prosperity is not the blessing that many might think. It often leads us to see our wealth as the source of our well being and can lead us to see God as irrelevant, inconsequential, and even unnecessary.

Comforts and amenities tend to blind us. Freedom from this soft prison lies with truth. The person who suffers cries out to the Lord. The person who is prosperous is annoyed by the crying of others.

Revelation 3:19 As many as I love, I rebuke and chasten: be zealous therefore, and repent.

Jesus calls Christians to turn from the enticement of comforts and rekindle zeal.

The usual ways of consuming water is either cold, or hot. Natural spring water is cold and such water heated up, and poured into a cup, becomes a 'hot cuppa'. Lukewarm water, on the other hand, is equated with stagnant pool-water; water that is usually not used for drinking but for bathing in. Lukewarm water is therefore dirty, impure, water. It is for that reason that God says that he can not drink that kind of water, and will spit it out.

Cold (spring) water stands for a moving, developing spirit. Hot water stands for having a burning zeal for God. These two are related, because the latter comes out of the former. Unrelated to the other two, lukewarm water, refers to spiritual stagnation.

Lukewarm is described in Revelation 3;17 as follows: Because thou sayest, I am rich, and increased with goods, and have need of nothing; and knowest not that thou art wretched and miserable, and poor, and blind and naked:

Revelation 3;18 I counsel thee to buy of me gold tried in the fire; that thou mayest be rich, and white raiment, that thou mayest be clothed, and that the shame of thy nakedness do not appear, and anoint thine eyes with eye-salve, that thou may see.

The phrase; "gold tried in the fire" lends itself to a purification process and could be construed as " hot" Those unsaved would be "cold". More importantly is the implication of purity.

Jeremiah 17;9-10 The heart is deceitful above all things, and desperately wickwd: Who can know it? I the LORD search the heart, I try every man according to his ways, and according to the fruits of his doings.

Some fruits of self deception are: Matthew 22;11-12 And when the king came in to see the guests, he saw there a man which had not on a wedding garment: And he saith unto him, Friend, how camest thou hither not having a wedding garment? And he was speechless. Matthew 7;22-23 Many will say to me in that day, LORD, LORD, have we not prophesied in thy name? and in thy name cast out devils? and in thy name done many wonderful works? And then will I profess unto them I never knew you: depart from me, ye that work iniquity.

The group in the church of Laodicea ignored the advice of James

James 1;22 But be ye doers of the word, and not hearers only, deceiving your own selves.

From the Wikipedia

However, a more recent interpretation has suggested that this metaphor has been drawn from the water supply of the city, which was lukewarm, in contrast to the hot springs at nearby Hierapolis and the cold, pure waters of Colossae. The archaeology shows Laodicea had an aqueduct that probably carried water from hot mineral springs some five miles south, which would have become tepid before entering the city (see main Laodicea article). The imagery of the Laodicean aqueduct suggests not that "hot" is good and "cold" is bad, but that both hot and cold water are useful, whereas lukewarm water is emetic

I think it is helpful to notice that there is a "Chiastic structure" in these seven letters to the churches in Revelation 2 and 3. There is a lot of literature describing "Chiastic structures", but for a quick explanation it describes the pattern where topics are discussed, and then revisited in reverse order. So the outline of topics in a Chiastic Structure might look like this:

• Topic 1
• • Topic 2
• • • Topic 3
• • Topic 2 (revisited)
• Topic 1 (revisited)

So, in the case of these letters to the 7 churches, we would pair the letter to Ephesus in Revelation 2:1-7 (as "topic 1") with the letter to Laodicea in Revelation 3:14-22 (as "topic 1 (revisited)".

Then we can see how we arrive at an explanation of "lukewarm" by reading that the admonition to Ephesus, which notices their "works, labor, patience", that they didn't bear with evil, etc, but He adds "Nevertheless I have somewhat against thee, because thou hast left thy first love" (verse 4). He follows this with an earnest appeal to repent.

When this topic is revisited in Laodicea, we see it developed as it would be in the hearts of believers who heard the admonition to Ephesus. He first takes up the outcome of those who didn't sincerely heed the call to repent. The "works, labor, patience" in Ephesus has now become "I know thy works, that thou art neither cold nor hot...". Having "left their first love" and continuing to not remember "from whence thou art fallen, and repent, and do the first works" (2:5) they now delude themselves into believing that they are "rich, and increased with goods, and have need of nothing;" (3:17) not knowing that in reality they are "wretched, and miserable, and poor, and blind"... and "lukewarm".

So the lukewarm state can be labeled "indifference". They were indifferent to the loving appeal to return to their first love, and then indifferent to their spiritual state that they eventually became.

In contrast, those who do respond to His appeal to repent and return to their first love would be seen described as having fellowship with Him: "if any man hear My voice, and open the door, I will come in to him, and will sup with him, and he with Me." (3:20)

In general, hot and cold are understood as being either strongly for God (on fire, passionate), strongly against God (cold to the things of God) and lukewarm as apathetic ( listless, having passion for neither side).

Example:

Clarke's Commentary on the Bible

Thou art neither cold nor hot - Ye are neither heathens nor Christians - neither good nor evil - neither led away by false doctrine, nor thoroughly addicted to that which is true. In a word, they were listless and indifferent, and seemed to care little whether heathenism or Christianity prevailed. Though they felt little zeal either for the salvation of their own souls or that of others, yet they had such a general conviction of the truth and importance of Christianity, that they could not readily give it up.

Also

Gill's Exposition of the Entire Bible

I know thy works,.... Which were far from being perfect, and not so good as those of the former church:

that thou art neither cold nor hot; she was not "cold", or without spiritual life, at least in many of her members, as all men by nature are, and carnal professors be; she was alive, but not lively: nor was she wholly without spiritual affections and love; to God, and Christ, to his people, ways, truths, and ordinances; she had love, but the fervency of it was abated: nor was she without spiritual breathings and desires altogether, as dead men are; or without the light and knowledge of the Gospel, and a profession of it, and yet she was not "hot"; her love to God and Christ, and the saints, was not ardent and flaming; it was not like coals of fire, that give most vehement flame, which many waters cannot quench the had not fervency of spirit in the service of the Lord; nor was she zealous for the truths of the Gospel, and for the ordinances of it, and for the house of God and its discipline; nor did she warmly oppose all sin, and every error and false way,

Laodicean meaning: lukewarm or indifferent in religion or politics

Laodicea was a wealthy city having a lukewarm water supply.

There can two possible meanings for the word "Lukewarm" in this verse.

1. Apathetic: The people in the Church of Laodicea were losing their enthusiasm for Jesus Christ and his ministries. They were satisfied with the spiritual blessings given to them when they received Jesus Christ. They simply enjoyed their salvation and had no zeal to preach the Gospel to the lost around them. They became stagnant and not giving out anything. Cold water is good for drinking, hot water is good for luxurious drinks, but lukewarm water is tasteless and better to spit it out. Jesus warned them that he will spit them out if they do not repent or change their attitudes.
2. Impure Faith: The church might have tolerated heathenism among the members and were serving both Jesus and other pagan gods, mixing their previous pagan beliefs with the new Christian beliefs. It could also mean they were serving both God and money. They were neither completely loyal to Jesus nor to their pagan gods or worldly things. Jesus was not happy with their services.

   Matthew 6:24 (NIV) "No one can serve two masters. Either you will hate the one and love the other, or you will be devoted to the one and despise the other. You cannot serve both God and money."