Languages let you express your thoughts so that other people can understand you. Read the following sentence aloud:

Now read it aloud again. Putting aside that repetition is a form of brainwashing, chances are that you made very similar sounds both times. When people speak in tongues, the phrase, “Our universe exists without meddling, omnipotent, omniscient entities,” in their supposedly supernatural language won’t sound the same twice. The reason is because they are making it up, just like everyone else who claims to talk in meaningful gibberish.

Try it: record them on your cell phone and play it back.

Peer pressure is interesting. If everybody around you is doing something, it becomes socially awkward to buck the trend. The Emperor's New Clothes is a great tale of such an incident. It took a young boy to courageously tell the Emperor of the tailor's joke: the Emperor was riding completely nude through the city streets. At that point, everyone started laughing and pointing at the Emperor. (Not a nice thing to do, mind you!)

Speaking in tongues is a lie to yourself and a lie to others.