Because lukewarm Christians don't usually try and cast out demons or prophecize (<----not a word lol)
Oh yes they do dear one, ...the lukewarm category are the ones who do this the most.
The cold ones are the Christians that have backslidden for some reason or another, they are cold concerning the things of the Lord, don't pray, go to church, read their Bible, fellowship with other Christians, they are these that Jesus talks about, ...a bruised reed He will not break and a smoldering wick He will not quench, those that are hot are those that do all of the aforementioned things, but have what we call zeal without knowledge, and Jesus knows how to discipline them to bring them under His control.
Those that are lukewarm are those in the Laodicean Church, the key to unlocking this is in the name, seven letters to seven churches, six are addressed to the church in the city, one is addressed to the people of the city, the signification of the word Laodicean is people's opinions, that means the church is being run by the people rather than by a pastor receiving his directions from Jesus, as explained to us in Rev 1:20, it is in the Laodicean church we find that well known verse that tells us Jesus is outside of the church Rev 3:20.
So put it all together, who do we find today seeing and casting out territorial demons around every corner, where do we find the famous prophets of God (that only have to be 65% correct), and miracles on demand, in what branches/denominations of the Church today?
Now, so to quiet any who might want to pick up rocks, Jesus tells us there are some in these dominations that are truly saved, but those that will be asking your question Paul talks about in 2 Thessalonians,
Do you not remember that I told you these things when I was still with you? And now you know what holds back, for him to be revealed in his own time. For the mystery of lawlessness is already working, only he is now holding back until it comes out of the midst. And then the lawless one will be revealed, whom the Lord shall consume with the breath of His mouth and shall destroy with the brightness of His coming, whose coming is according to the working of Satan with all power and signs and lying wonders, and with all deceit of unrighteousness in those who perish, because they did not receive the love of the truth, so that they might be saved. And for this cause God shall send them strong delusion, that they should believe a lie, so that all those who do not believe the truth, but delight in unrighteousness, might be condemned. 2Th 2:5-12
They perish because they did not receive a love for the truth, so they believed the lying signs and wonders that are so prevalent in the Apostate church today, because they didn't want to believe the Truth God will send a strong delusion on them so that they will believe the lie (What lie? You will be like God, ...now how many posts here on this forum have you read this very doctrine?) and they will continue on with their false gospel and doctrine thinking all the time they are right, ...the next step in this parade is the rapture of the Lord's Bride, those that are deluded, the Apostate church, will continue on until they die during the Tribulation, their soul will be taken to Hell and there they will be waiting for the Great White Throne Judgement so they can present their unjust treatment by the Lord and give their defense,
‘Lord! Lord! We prophesied in your name and cast out demons in your name and performed many miracles in your name.’
Can't you just hear them saying that, unfortunately, we will know some of them by their name on this forum, how sad, ...but Jesus told us there would be tares in the wheat field. Blessings, Gene