We must be sober and watchful, and beg God for the gift of discernment.
Personally, I believe in the Holy Fire because several of my close friends have been to Jerusalem and they have their hands in the Holy Fire without getting burned, and then put their entire face into the flame without a single hair being burnt. It is significant that when the New Calendar and New Style "Catholic" Pascalion was being observed in 1924 by the EP and the Greek Church, the Holy Fire did not ignite on the day when Catholics and the EP celebrated Easter. Since the faithful rose up against this novel change in the Pascalion, the EP was forced to change the Pascalion back to the Orthodox date of Pascha, while retaining the New Calendar for the rest of the year. Thus, one can see the devious agenda of the EP which was unmasked by the Orthodox faithful. If the EP had not changed from the Catholic Easter back to the Orthodox Pascha, then few people would be observing the New Calendar as it stands today.
There have been several incidents at Mount Athos where monks have disobeyed their elder's caution not to go chasing after miracles because the devil himself will work wonders that may even deceive monks and elders. While some of these monks ended up dying in strange circumstances, others were spared by the grace of God, so that they were able to repent, confess their disobedience, and thus warn their fellow monks to be sober and watchful (read the first epistle of St. Peter).
We are also told that the AntiChrist will work signs and wonders.