"Speaking in Tongues" is still practiced in my home town in several of the Pentecostal churches. It is in this URL reference (below) that, for the first time, I've ever heard mentioned the OLD Tongue and the New Tongue. So I must presume that those who are "overcome" during a gathering in the Church are considered to be speaking in the New Tongue, although I'm not sure that anyone who is not also smitten at the same time would know if two or more speaking in Tongue can actually understand what each other is saying... LOLhttp://www.tbm.org/tongues.htm
And, look at the Biblical Account of the of "The Tower of Babel." Speaking in Tongueshttp://ldolphin.org/babel.htm
I have two theories of thought on this subject.
If we substitute the word "Progenitors" or "Overlords" for the word "Lord" we can presume that the off-world hierarchy who seeded Earth found mankind had ascended enough in growth (mental and strength of physicality) that having so many of us in understanding and agreement, able to work together for the same goal, was indeed a THREAT to the progenitors, and so they used technology to alter the synapses in the brains so that only some family branches could understand each other, while they could no longer understand the voices of their cousins, who could not understand all of their family branches, either...(Perhaps targeted the difference in the DNA of the family lines of the different siblings, much like what our own science is endeavoring to do today!)
And since understanding conversation was absolutely necessary for them all to work together in harmony, each group who could still understand each other, left and went somewhere else, away from the consternation that prevailed when they were with others speaking "nonsense."
If the Overlords wanted to (so to speak) Divide & keep us Conquered and under their control for hundreds of thousands of years to come, the altering of our abilities to communicate with each other has served the Overlords well for a very long time. As long as we don't understand each others' languages, religions, traditions, etc., we cannot be expected to stop warring with each other. Hence, "divide & conquer" or keep us enslaved in ignorance, fighting personal battles instead of being a greater threat to whatever is OUT THERE
... beyond the confines of Earth's gravity, has worked well.
Now that we are back to learning each others' languages again, for the sake of world-wide business ventures, we are no longer the segregated nations we used to be. In another 200-400 years, providing we don't blow ourselves up, suffer a disaster from a meteor, or become CONFUSED
again by those who are "out there" watching all that's being learned and being accomplished, we might once again become that same kind of threat
we'd become according to religious stories, whether the Biblical Timeline can be trusted as accurate, or not!
(I tend to think some stories happened many times in many different places throughout the billions of years Earth and the Universe has existed. And therefore timelines and events might have become all jumbled up--for example, the FLOOD in the Christian Bible might have been listed at the time that a flood happened in India, or China, or on a completely different planet! Perhaps The Garden of Eden was an "experiment" being conducted on several planets in several solar systems at the same time, or at different times, but the legends keep getting passed down through the surviving energies or souls, as we migrate from time-to-time and place-to-place.)
True, we haven't all adopted one primary language, yet... (most scholars now think it will be some form of Chinese, instead of French or English, as it has been for a hundred years) but as long as we don't kill ourselves, or become a tremendous threat to the Overlords, again, perhaps we really WILL be able to all speak one language that we all can understand, as well as several others. And when that happens, barriers are torn down... traditions become understood and changed; knowledge is readily exchanged instead of blood and ammo. There's SO MUCH we could accomplish if we could all understand each other, and work together for common goals.
In summary, perhaps speaking in Tongues is no more or less a threat than tapping into our ancestors' root languages. Connecting a synapsis to a buried memory which has traversed Time, gender, space, knowledge, and potential genocide. Prayer and Meditation can both yield tremendous emotional and biological responses, and thus are very similar in practice. So perhaps the Tongues languages share a similarity about which we can only guess, until we have proof that the languages were valid (even if outdated, like Sumarian or Greek) or are still spoken in some solar system, just a dimension away.