Want Some Answers ???
Thanks for writing. Although you don't mention anything I have written, you have much to say about "evangelicals" and it's all bad. In fact you describe them as a cult [and for that matter all others fit your definition as well]. The word 'evangelical' (like 'Christian') has a wide circle of professors. And good and bad things can be said about them. Anyone can state things about 'evangelicals' they regard unbiblical, while claiming greater allegiance to the Bible themselves.
But my first thoughts regarding your email are that you are apart of what evangelicals call a 'cult' and that disturbs you. Anyone with such venom for evangelicals is likely from a radical heretical sect outside traditional Christianity. So which group are you from? I suspect you are either Jehovah's Witness or Christadelphian. Both hide their identity [which you do] and pretend to be, and try to sound 'Christian' yet even better.
Your thesis fails on two accounts. The Bible is all about bringing a man to the knowledge of Christ as Saviour. Salvation is a message for all, not just those in one special group. But invariably those in the cults have never accepted Christ as Saviour. They claim to follow Christ yet they are NOT God's children [Mt.7:22-23]. Freedom of speech and freedom to hold various shades of doctrine is an evangelical tradition. But not so among the cults they are clones of their sect (true of you?). They insist everyone MUST follow their particular doctrines and practice to earn eternal life. At least 'evangelical' churches preach the Good News of the gospel, which cults don't. The Bible declares the Good News, which anyone can read and no one needs the writings of a cult to know it.
Another thing about those in cults is that they are close-minded when others will see the light and understand the truth. They refuse to see while others would be willing [2 Cor.4:4]. Facts and truth make no difference to them. They are zealous for the doctrines of their sect rather than for "the doctrine of Christ" [1 Jn.9]. And they are hostile to traditional Christianity [which you are well aware of].
Your definition fails because you don't know what truth is. You think truth is a system of ideas [or doctrines] if you get them correct - you know the truth. It's not. The truth is a Person. Jesus said, "I am the way the truth and the life, no man comes to the father but by me'. [Jn.14:6]. When a man comes to Christ and accepts Him as Saviour, they have found and know the Truth. It doesn't mean they know everything or are never wrong on some point, but it means they have the truth in the Person of Christ.
You see Christianity is all about a relationship. It's a focus on a Person. It's not about how many PhD's one has, or how many good deeds. In all sects, cults and heresies their leaders point a way to God, but in true Christianity Jesus points to Himself as God. So I would say the true Biblical definition of a cult is a group that don't teach the gospel of salvation but simply demand a religious observance of doctrines it calls true.