Lucian, I would like to challenge your approach to 'proving' what is heretical vs. authentic. Your post appears to suggest that you are allowing miracles to 'prove' truth. I would challenge you that truth should prove all things by itself.
I assume you're Orthodox? I think we can establish a base that we can both agree with - that the Bible is the inspired, inerrant Word of God. God Himself inspired its writing, and the prophecy came not in old time by the will of man: but holy men of God spake as they were moved by the Holy Ghost (2 Peter 1:21). Can we start with the agreement that the Bible is God's direct Word to mankind?
As God is Holy, True and Perfect, so His Word is True. It cannot be anything but True. Therefore, we can judge all things by it. We are, in fact, instructed to prove all things; hold fast that which is true (1 Thess. 5:21). Consider:
And the brethren immediately sent away Paul and Silas by night unto Berea: who coming thither went into the synagogue of the Jews. These were more noble than those in Thessalonica, in that they received the word with all readiness of mind, and searched the scriptures daily, whether those things were so. Therefore many of them believed; also of honourable women which were Greeks, and of men, not a few. (Acts 17:10-12)
So we are told to look in the Bible to see if what we are taught by other sources is true. Consider also:
For we have not followed cunningly devised fables, when we made known unto you the power and coming of our Lord Jesus Christ, but were eyewitnesses of his majesty. For he received from God the Father honour and glory, when there came such a voice to him from the excellent glory, This is my beloved Son, in whom I am well pleased. And this voice which came from heaven we heard, when we were with him in the holy mount. We have also a more sure word of prophecy; whereunto ye do well that ye take heed, as unto a light that shineth in a dark place, until the day dawn, and the day star arise in your hearts: Knowing this first, that no prophecy of the scripture is of any private interpretation. For the prophecy came not in old time by the will of man: but holy men of God spake as they were moved by the Holy Ghost. (2 Peter 1:16-21)
Here Peter is referring to the Transfiguration described in Matthew 17. This was an amazing, miraculous event where the disciples not only saw Jesus as God in His glory, but also saw the great (dead) prophets speaking to Him! What an amazing sign and event this was - yet Peter tells us in this passage that the written Word of God (the Bible) is a more sure source of information and truth (i.e. prophecy) than that miraculous sign. The principle here is that the Bible is to be our first source of Truth - more so than any sign.
We do see in the Bible where at different times, God used signs & wonders - especially in His dealing with the Jews. But that was never His primary form of communication. God sent prophets to tell His people His truth; many of those prophets He used to write down His Word in the Bible. O Jerusalem, Jerusalem, thou that killest the prophets, and stonest them which are sent unto thee, how often would I have gathered thy children together, even as a hen gathereth her chickens under her wings, and ye would not! (Matthew 23:37). Moreover, we are repeatedly warned that there will be false prophets, and false christs, that will use signs and wonders to deceive people:
Even him, whose coming is after the working of Satan with all power and signs and lying wonders... (2 Thess. 2:9)
And many false prophets shall rise, and shall deceive many... Then if any man shall say unto you, Lo, here is Christ, or there; believe it not. For there shall arise false Christs, and false prophets, and shall shew great signs and wonders; insomuch that, if it were possible, they shall deceive the very elect. Behold, I have told you before. (Matthew 24:11, 23-25) (Mark 13:21-22)
And I beheld another beast coming up out of the earth; and he had two horns like a lamb, and he spake as a dragon. And he exerciseth all the power of the first beast before him, and causeth the earth and them which dwell therein to worship the first beast, whose deadly wound was healed. And he doeth great wonders, so that he maketh fire come down from heaven on the earth in the sight of men, And deceiveth them that dwell on the earth by the means of those miracles which he had power to do in the sight of the beast... (Rev. 13:11-14a)
This last one specifically refers to fire being used as a false sign!
Remember also, that in the time of the Exodus, the priests of the false Egyptian gods were able to recreate some of the miracles of the plagues. Satan is not without power, and uses that power to deceive people lest they believe in the true Gospel of God and be saved.
And the magicians of Egypt did so with their enchantments: and Pharaoh's heart was hardened, neither did he hearken unto them; as the Lord had said. And the magicians did so with their enchantments, and brought up frogs upon the land of Egypt. (Exodus 7:22; 8:17)
This, then, is what the Bible says about all signs and wonders; that they must be proven by Scripture, that Scripture is always the final Word, and that they can be the work of false prophets and must not be implicitly trusted. Is this Holy Fire used to demonstrate the veracity of Orthodoxy? Then one must look at the doctrine of Orthodoxy. How does it compare to the Bible? Ephesians 2:5-6 says: For by grace are ye saved through faith; and that not of yourselves: it is the gift of God:Not of works, lest any man should boast. Is Orthodox doctrine in agreement with this? Does it agree with the teaching of Isaiah 53 and the rest of Scripture which teach that Christ is our substitutionary atonement - that God literally accepted His Death as sacrifice for sin in our stead? If not, you must reject the doctrines of men in favor of the teaching of the Word of God. Trying to worship God using the doctrines of men is vain. Look at Matthew 15:9 (But in vain they do worship me, teaching for doctrines the commandments of men) and Mark 7:7; study Colossians 2 which warns about replacing the simple Gospel of faith in Jesus Christ's finished work alone for a works-based attempt at pleasing God. (which can never succeed: But we are all as an unclean thing, and all our righteousnesses are as filthy rags; and we all do fade as a leaf; and our iniquities, like the wind, have taken us away. Isaiah 64:6)
You had asked what I thought about the Holy Fire. First, my library training (I'm a Library Tech by education) teaches me not to trust a site that has an inherent interest in the subject. In other words, of course an Orthodox site will cite proof for this phenomenon. Any claim of scientific proof needs to be backed up by an impartial witness. Secondly, a quick Wikipedia search shows that this phenomenon has apparently been debunked by multiple individuals over the past millennium. Thirdly, (and actually the most important), since the Bible warns me of false teachers using miracles, and since I know Orthodox doctrine is not in line with the Bible, I honestly don't care whether it's an authentic miracle or a hoax. It could be a miracle of Satan, or it could be a hoax of the priests. Doesn't matter. I will trust the Bible, God's Word, as True and Truth and follow its teachings rather than that of the Orthodox church.
Food for thought. I was not 'raised Baptist', rather as a born-again believer I choose to attend the Baptist church that I do because I believe its teachings align most closely with the Bible.