Even in the case of lifeless things that make sounds, such as the pipe or harp, how will anyone know what tune is being played unless there is a distinction in the notes?
Again, if the trumpet does not sound a clear call, who will get ready for battle?
So it is with you. Unless you speak intelligible words with your tongue, how will anyone know what you are saying? You will just be speaking into the air.
Undoubtedly there are all sorts of languages in the world, yet none of them is without meaning.
If then I do not grasp the meaning of what someone is saying, I am a foreigner to the speaker, and the speaker is a foreigner to me.
So it is with you. Since you are eager for gifts of the Spirit, try to excel in those that build up the church.
For this reason the one who speaks in a tongue should pray that they may interpret what they say.
For if I pray in a tongue, my spirit prays, but my mind is unfruitful.
So what shall I do? I will pray with my spirit, but I will also pray with my understanding; I will sing with my spirit, but I will also sing with my understanding.
Otherwise when you are praising God in the Spirit, how can someone else, who is now put in the position of an inquirer, say “Amen” to your thanksgiving, since they do not know what you are saying?
You are giving thanks well enough, but no one else is edified.