Dearest FunkyD... may you have peace!
The word of my Lord, the Son of God, JAHESHUA MISCHAJAH, to you is that with regard to BOTH groups... 'by their fruits you will know them'... as manifested by the 'gifts' of God's spirit... or by the lack thereof.
But this does not distinguish the sons from those mentally ill, for in truth, even a chosen one may suffer from 'mental illness', as THIS world defines it. Trust me, I have been called such (and worse) more than once, even here. Virtually every prophet was accused of insanity. Even my Lord himself was thought 'mad'. But that is because THIS world ALWAYS puts a label of madness... or inferiority... on that which is 'different'... or inexplicable (by them).
And... there are those who claim to be 'anointed', who are NOT... and are also not considered 'mentally ill'. Yet, of such ones, my Lord will say, "Get away from me; I never KNEW you!"
May I offer a suggestion? Unless it is OBVIOUS that one is not a son of God (as evidenced by his similarlity to Cain, borne out in 'hatred' for his 'brother'), and since ALL creation is awaiting the revealing of the sons of God, would it not behoove ALL of us to treat one another AS IF we were ALL Christ's brothers, anointed with holy spirit? Truly, what is the harm in doing so? Even if such one professes a different faith, what is the harm? For indeed, even if such one PROVES themselves not to be a son of God, by means of emulating Cain... who hated his brother... are we not obligated to show even that one... one who may be our 'enemy'... love... and continue praying for them?
True, we are not to LISTEN to everyone, but rather, 'test the inspired expression because not all inspired expressions originate with God.' So, we DO have ways to know, don't we?
This very issue that you've raised exists, however, because of religion's (and particularly the WTBTS') erroneous raising up above others of such ones, creating two or more classes and therefore 'dividing' God... and dividing the Christ: the whole 'who is anointed, who is not'... 'who is worthy; who is not'... 'who can be; who cannot'... 'who is 'right', who is 'righteous', who is not'... they look like this; they don't look like that'... 'that one can't be'... melarkey. But that is THEIR way... the way of the WORLD. Judging based on OUTWARD appearances. It is NOT, however, to be the way of the sons of God. Just as our Father does not judge based on outward appearances, as He is NOT 'partial' so that the man the fears him... and 'works righteousness'... is acceptable to Him. Thus, even appearance of 'madness' means nothing to HIM; neither should it to us.
As for the WTBTS, they SAY, "It is a matter between the person and God and not for anyone else to say...", yes? But then they turn right around and judge who is... and who is not... while saying that they don't. Thus, I repeat to you the words of my Lord as recorded at Matthew 23:3...
"All things they tell you, do and observe...
but do not do according to THEIR deeds,
for they say... but do not perform."
I hope I have been able to help you, FunkyD. For I have spoken it to you, just as I myself have heard and received it from my Lord, the Son of the Holy One of Israel, JAH OF ARMIES... whose name is JAHESHUA MISCHAJAH.
Again, I bid you peace.
Your servant and a slave of Christ,