Hoist by your own petard, ... Baptists, according to you, ... know the state of someone's heart and relationship with God
Oh dear! I understand a petard
is a small bomb. Alas!
But seriously, I think this is verification of the title of this thread "I don't understand the Evangelical mindset" (though I hope not of the conclusion, "never will!" I'll do what I can to help.
I suspect that we each come over to each other as proud and arrogant: we to you for the reason given in your post; you to us for the claim that you are the only true Church, and its converse that we are heretics, schismatics and sons of Judas Iscariot. In reality, if one takes the trouble to understand why
Orthodox make that astonishing claim, it makes sense, and one can understand without agreeing. (Of course, it can
produce Orthodox pride, but that is another matter.)
Similarly, I think if you can come to understand how we 'tick', you may continue to disagree, but you may at least concede that our thoughts do not arise from pride or arrogance.
For one thing, you only have to look at our hymnbooks, which sort-of function as a liturgy, to see the many many expressions of astonishment along the lines of, How can God possibly love and forgive such a guilty and wretched sinner as me?
In itself that ought to give you a clue that something other than pride is operative here.
You often talk about 'mystical' matters, and I may find it hard to put into words, but there is an indefinable something
that enables those who are born of God to recognise the 'family relationship', the onesss in Christ, the brotherhood as children of God, which transcends denominational barriers. It is recognising instinctively that "this person knows and loves the same Lord as I do", whether "this person" is Protestant, Catholic or Orthodox.
Of course this Christian instinct, though (I believe) God-given, is not infallible, and of course we sometimes believe someone is 'saved' when he is not, and sometimes think someone isn't when he is. None of us is inerrant. But in general terms, if a person is born of God, there is something about his spirit, his conversation, his awareness of Christ, that marks him out as such.
It has nothing to do with pride or arrogance, but rather with brothers and sisters in Christ normally recognising each other as such. Such may be very wealthy Brits, or very poor Albanian gypsies, or anything else: but the sense of fraternity in Christ is there.
"Why" you might ask "do we not recognise it so often and so easily in Catholics and Orthodox?" Probably partly (as I wrote earlier) because we have little contact with them; but partly because you do not (if I understand aright) encourage assurance of salvation, and therefore you talk about your spiritual experience in different terms from ours, and we misunderstand one another. But this can be, and often is, overcome, when people sit down together and talk face to face, get to know each other, and discover that Christ has been made real to each.