I've been having an online discussion with a man who claims that "Speaking in Tongues" involves speaking in an angelic, divine or invented language without understanding anything you're saying. I've countered that the Biblical examples of Speaking in Tongues, such as when the apostles spoke in tongues on Pentecost, involved speaking a language despite having never been taught it, but understanding what was being said. He countered by asking, "why bother to mentioned if it is just understandable language?"
I responded by pointing out they were speaking in a language they had not learned, but was a real language. one has to remember that 1st century Palestine was a melting pot of cultures, but not everyone understood each other. Traveling more than a few days or weeks away would require you to find a translator. Traveling more than a few months would mean it would be nearly miraculous to even FIND someone who spoke both your language and the native language. Even traveling within the Roman Empire and knowing Latin would only let you speak to the educated, not the masses.
Remember the Tower of Babel? When the apostles spoke in tongues on Pentecost they were undoing that curse.
The ease with which one can find a translator these days and the mind boggling scope of a few spoken languages makes it easy to discount the amazing power of the Pentecost miracle of speaking in tongues. I can understand why false prophets try and claim the gift involves speaking in an angelic language despite the complete lack of Biblical support for the claim. When you can enroll at the local university and learn just about any language you want it's easy to forget just how incredible the gift of tongues, speaking to people in their own language despite having never been taught it, really is.
They didn't HAVE university courses in other languages back then. You couldn't go to Borders, pick up a "Spanish 101" DVD series and have a rudimentary understanding of the language in a few months. You needed to either travel to a place and immerse yourself for months to years, or hire one or more tutors. Most people only spoke the languages of their immediate neighbors. Only the wealthy and traders could afford to learn more languages than they grew up with.
And here were these fishermen, these uneducated working class stiffs running around speaking the language of the people who had traveled for weeks or months to be in Jerusalem for passover. The travelers would have been blown away by this. Here they were, needing translators or speaking a pidgin Latin or Hebrew, desperately trying to communicate even the most rudimentary ideas, suddenly being approached by a fisherman who spoke their language with the fluency of a native speaker yet were obviously working class men from the immediate area.
The miracle looses all substance if the Apostles didn't understand what they were saying. Instead of being miraculously connected to visiting foreigners they'd be nothing but a marionette. The visitors would have seen uneducated nobodies reciting a memorized speech. That's not a miracle. That's no better than rote memorization.