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Most Bible students agree that the tongues spoken in the book of Acts were normal languages of the world (Acts 2, 10, and 19). But some add that there is a second gift – a heavenly prayer language. This latter gift, they say, is to express the Spirit’s “groanings which cannot be uttered” (Romans 8:26).
This doctrine of a prayer language is based on this verse “For if I pray in an unknown tongue, my spirit prayeth, but my understanding is unfruitful” (1 Corinthians 14:14). They interpret this to mean that when Paul prayed in the Spirit, he used a “heavenly tongue” and did not himself know what he was praying. But if this is true how would the supplicant ever know if his prayer was answered?
So, what is Paul really saying in 1 Corinthians 14:14? The problem in understanding this verse comes largely from the translation. If we rephrase the verse it will say: “If I pray in a language those around me do not know, I might be praying with the Spirit, but my thoughts would be unfruitful for those listening.” Paul is saying, we should either pray so others around us can understand or else keep quiet! “What is it then? I will pray with the spirit, and I will pray with the understanding also: I will sing with the spirit, and I will sing with the understanding also. Else when thou shalt bless with the spirit, how shall he that occupieth the room of the unlearned say Amen at thy giving of thanks, seeing he understandeth not what thou sayest?” (1 Corinthians 14:15, 16).
According to this text, who has the problem with understanding? It is the listener and not the speaker as is commonly taught. If you have ever prayed with someone who is offering a prayer in a language unknown to you, then you know what Paul meant when he said it is difficult for you to say “Amen” at the end of the prayer. Without an interpreter, you have no idea to what you are assenting.
It is obvious from the context of 1 Corinthians 14 that the purpose of speaking in tongues, or foreign languages, is to communicate the gospel. If the listeners do not understand the spoken language they cannot be edified. Consequently, if there is no interpreter, the speaker is simply speaking into the air and the only ones present who know what is being said are God and himself. This is the clear meaning of the often-misquoted verse (2) “For he that speaketh in an unknown tongue speaketh not unto men, but unto God: for no man understandeth him; howbeit in the spirit he speaketh mysteries.”
Paul emphasizes again that the languages spoken need to be understood by the hearers “So likewise ye; except ye utter by tongue words easy to be understood, how shall it be known what is spoken? for ye shall speak into the air.” “But if there be no interpreter, let him keep silence in the church; and let him speak to himself, and to God” (verses 9, 28).
The whole purpose of tongues is to communicate the gospel: http://www.proofdirectory.org/whats-the-purpose-of-giving-the-gift-of-tongues/
For more on the gift of tongues and its use today: http://www.proofdirectory.org/some-churches-stress-receiving-the-gift-of-tongues-more-than-other-gifts-is-this-biblical/
For more on the meaning of speaking in tongues: http://www.proofdirectory.org/what-does-it-mean-to-speak-in-tongues/
In His service,