Elder, the things that are said by those who go over to the Pentecostals – that is, about seeing visions, speaking in tongues, etc. – are those things from their own imagination, or from demonic influences?
They are energies of demonic influences; because when they go over to the Pentecostals and are re-baptized, they are actually disregarding and denying Holy Baptism: "I confess one Baptism, for the remission of sins," as the Creed declares. Thus, they un-baptize themselves and become susceptible to demonic influences and then they jabber-jabber, supposedly in tongues. "It is the Holy Spirit of Pentecost talking" they tell us. But it is not the Holy Spirit; it is a whole lot of unclean spirits. What tongues? They are merely uttering gibberish, which not even they can comprehend. They even record that gibberish and then produce statistics and reach conclusions: "That tongue has so many ‘hallelujahs’ in it, and there are so many in the other tongue…" Well, it’s to be expected, among so much jabber-jabber, you will surely hear something that resembles the word ‘hallelujah’ in one of the languages of the world! And so you can see, while it is something demonic, they actually believe that which is demonic to be the energy of the Holy Spirit, and that they are supposedly experiencing what the Apostles had experienced on the day of the Pentecost! Blasphemies are the things they believe, which is why they become demon-possessed.
Elder, why are they re-baptized?
Because they claim: "When I was baptized, I was young and didn’t know; now I am baptized and fully aware." They are re-baptized, and thus justify their sins. If the Church didn’t have infant Baptism, what would happen to infants in case of death before their Baptism? That is why a godparent becomes the child’s guarantor and recites the Creed and bears responsibility for the child until it is of age. Is the child treated unfairly, simply for being Baptized young? No; on the contrary it is helped because it receives Holy Communion. And when the child has grown up and is baptized, even if any sin is committed, there is always repentance and confession, which can wash away that sin – not by going to be baptized again!
From Elder Paisios' Spiritual Counsels: Spiritual Struggle, vol. 3.