Have you even bothered to read my testimony in my tongues thread? If you are honest enough to learn about experiences you haven't had and judgmentally condemn, you would realize that my outpouring of tongues saved me from agnosticism and set my heart on fire to witness to power of the Gospel of Christ's saving atonement. As Jesus taught, "By their fruits you will know them." In an age in which the US church has for several decades been in slow steady decline (losing 20% of its membership in the last 20 years), the Pentecostal movement has grown to 600 million converts, one quarter of the world's Christian population, and continues to grow in leaps and bounds under the mighty anointing of the Holy Spirit. And you, sir, need to study how the NT church understood the sin of blaspheming against the Holy Spirit because you are in danger of having committed it! Read Didache 11:7, a verse that expresses the NT churches understanding of this sin from around 95 AD.
The way to see if its true is like how they check money, the test of a counterfeit bill is simply to compare it with a genuine bill. It is impossible to know without a genuine, for otherwise you have no basis for comparison or standard of measurement. This is always the test of falsehood and we see that the gift was so that other Jews from the diaspora could understand the gospel being given them. Failure to see this is one of the reasons why people start false speaking in tongues or charismatic manifestations and they are "told' it is from the Holy Spirit, yet there is no understanding or any interpretation or any sense of true language, just gibberish, and shaking, and falling, and pure demonic possession. We have to read the scripture to discover the characteristics of the genuine gift of tongues in order that we might compare what we hear, and evaluate it as true or false, and see whether it is genuinely of the Spirit of God, or comes from another source and is a counterfeit gift. The only way that we can possibly know this is to lay it alongside that which is unquestionably true. We know what it is in the islands, those who are possessed with this counterfeit spirit are not bearing the fruits of the Spirit, but rather the works of the flesh. Scripture has many text with the true being compared to the counterfeit.
Galatians 5:19-23
19 Now the works of the flesh are manifest, which are these; Adultery, fornication, uncleanness, lasciviousness,
20 Idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies,
21 Envyings, murders, drunkenness, revellings, and such like: of the which I tell you before, as I have also told you in time past, that they which do such things shall not inherit the kingdom of God.
22 But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith,
23 Meekness, temperance: against such there is no law.