When someone does this, the Bible says you can’t say “amen” to their prayer. Let me explain why. The word “Amen” means “truly” or “I agree”. So, when you say “amen” to a prayer, you are saying “I agree with this prayer”. If someone says a prayer that you don’t understand, you can’t say “amen” because you don’t know what you are agreeing with.

“Otherwise, if you bless with the spirit, how will he who occupies the place of the uninformed say “Amen” at your giving of thanks, since he does not understand what you say? For you indeed give thanks well, but the other is not edified. I thank my God I speak with tongues more than you all; yet in the church I would rather speak five words with my understanding, that I may teach others also, than ten thousand words in a tongue. ”
– 1 Corinthians 14:16-19

This is referring to someone praying in tongues without interpretation. When this happens, you don’t know if the person is praising God or cursing Him. You don’t know if they are blaspheming or blessing. So, you can’t say “amen” in agreement with their prayer because you don’t know what they said.

Paul argues that five edifying words is better than ten thousand words in an unknown language. Why? Because we need to edify others. That’s why Paul encourages the use of spiritual gifts for the purpose of edifying others.

“But he who prophesies speaks EDIFICATION and EXHORTATION and COMFORT to men. He who speaks in a tongue edifies himself, but he who prophesies EDIFIES THE CHURCH. I wish you all spoke with tongues, but even more that you prophesied; for he who prophesies is greater than he who speaks with tongues, UNLESS INDEED HE INTERPRETS, THAT THE CHURCH MAY RECEIVE EDIFICATION.”
– 1 Corinthians 14:3-5

Prophecy is greater than tongues because it brings edification to the church unless there is an interpretation for the tongues because the interpretation brings edification to the church.

We see that tongues without interpretation only edifies the person speaking. But that’s not the purpose of Spiritual Gifts. Spiritual gifts are not given for our own edification. The gifts are given for the edification of others.

“Even so you, since you are zealous for spiritual gifts, let it be for the edification of the church that you seek to excel. ”
– 1 Corinthians 14:12

Speaking in tongues is a Biblical gift of the Spirit, and it has a purpose. Unfortunately, many people who claim to be speaking in tongues do so without interpretation, and if there is no interpretation, it’s out of place and serves no purpose in the church.

If no one knows what you said, then what is the purpose in saying it?

“So likewise you, unless you utter by the tongue words easy to understand, how will it be known what is spoken? For you will be speaking into the air. There are, it may be, so many kinds of languages in the world, and none of them is without significance. Therefore, if I do not know the meaning of the language, I shall be a foreigner to him who speaks, and he who speaks will be a foreigner to me.”
– 1 Corinthians 14:9-11

Speaking in tongues is a gift of the Holy Spirit, and it is encouraged, but there should always be some sort of interpretation so that people can understand and be edified by it. Otherwise, you’re just alienating people.

Speaking in a way that people understand is important, and this extends beyond tongues. Some people like to use big words to sound important, but if the hearer doesn’t understand the big fancy words they use, it doesn’t do them any good. It doesn’t edify them.

We need to do our best to communicate clearly so that people are edified by what we say.

“What is the conclusion then? I will pray with the spirit, and I will also pray with the understanding. I will sing with the spirit, and I will also sing with the understanding. Otherwise, if you bless with the spirit, how will he who occupies the place of the uninformed say “Amen” at your giving of thanks, since he does not understand what you say?”
– 1 Corinthians 14:15-16

Bringing understanding is important in any form of communication, and when tongues are involved, that means interpretation is important, even in prayer. Because how can people say “amen” if they don’t know what you are praying for?