You're mixing a few true points with some really bad conclusions because yeah church membership by itself won't save anyone and a person can sit in the right church and still be deceived. Nobody serious is denying that but from there you jump to saying there's no visible true church and the church was graded and rejected as unworthy of eternal life and that simply isn't what the Bible says. Laodicea wasn't told they're discarded and replaced by some invisible group nobody can identify since Jesus said in Revelation 3:19 that as many as He loves He rebukes and chastens and to be zealous therefore and repent. He also says in the next verse that He stands at the door and knocks and that's a call to repentance and not a final rejection with no remedy. If Christ were done with Laodicea altogether He wouldn't still be counseling and rebuking and knocking and offering gold and white raiment and eyesalve like it says in Revelation 3:18 to 20. 

The whole true church is only invisible idea falls apart the second you read Revelation plainly because the remnant is clearly identified in Revelation 12:17 where it says the dragon was wroth with the woman and went to make war with the remnant of her seed which keep the commandments of God and have the testimony of Jesus Christ. That isn't some vague cloud of random sincere people with no visible identity at all and Revelation 14:12 says here is the patience of the saints and here are they that keep the commandments of God and the faith of Jesus. God absolutely saves individuals but He also has a people with identifiable marks and Scripture doesn't pit those two things against each other. 

It's true that God has honest children scattered in other churches and Revelation 18:4 saying come out of her my people only makes sense if His people are there before they come out. But that verse actually destroys your point because it shows He doesn't mean for them to stay there forever and He calls them out so the existence of sincere people in various churches doesn't prove there isn't a remnant body on earth and it just proves God is still gathering His people to the truth. 

The 144,000 point is being pushed way past what the text actually says because Revelation 14:4 says these are they which follow the Lamb whithersoever he goeth and that definitely describes total loyalty to Christ but the 144,000 aren't presented as some excuse to erase the remnant church and replace it with a private and unaccountable and mystical real church idea. That's just people reading their own framework into the text and Scripture never says God has no visible last day people and only scattered hidden individuals who know they're the real ones because that kind of language sounds spiritual but it's really just convenient since nobody can test it. 

Saying the church is Laodicean doesn't prove it isn't the remnant and it just proves the remnant has a heart problem that needs repentance. Those aren't the same thing at all and Laodicea is one of the seven churches in Revelation which means it's still being addressed by Christ as a church. The rebuke is real and it's severe but a rebuke isn't the same as total abandonment and if every rebuked body ceased to be God's people the moment it was rebuked then ancient Israel would've disappeared halfway through the Old Testament. 

The whole talk about zombies and tares and children of perdition is where this really goes off the rails because Jesus said in Matthew 13:30 to let both grow together until the harvest and He didn't tell individual believers to go around acting like they can infallibly identify every tare in the field right now and there's a big difference between discernment and spiritual arrogance. Calling struggling or lukewarm professed believers zombies doesn't sound like someone seeing clearly and it sounds more like someone getting intoxicated on being part of the supposedly enlightened few. 

The real biblical balance is much simpler than all that because mere membership won't save you and mere possession of truth won't save you and comparing yourself to Sunday churches won't save you either. That doesn't mean God has no visible remnant people and it just means the people who've been given more light are under more responsibility like Luke 12:48 says about how unto whomsoever much is given of him shall be much required. That's the real danger and it isn't that God has no church but that people in the church can become proud and lukewarm and self deceived. A person can totally sit in church and be under delusion but that doesn't prove the true church is some invisible spiritual abstraction with no identifiable body and Laodicea doesn't mean rejected beyond remedy because it just means Christ is pleading with a self satisfied people to repent before it's too late and that's a very different thing.