Pentecostals allege that the tongues they speak today is a heavenly language. A language that can only be understood by God and the angels. The benefits of this language is said to be that it is a confirmation of one's salvation and it also is a faster way of communicating an urgent prayer for Divine intervention. An example would be if you witnessed a catastrophic car crash; by uttering a quick prayer to God, He could intervene for the individuals involved.
So what does the Bible say regarding "the unknown tongue" and the language or "tongue of angels"? Is this really a heavenly language or is it a gross misinterpretation of Scriptural context?
The only place in NT Scripture where an "unknown tongue" is mentioned is in 1 Corinthians 14:4, KJV, "He that speaketh in an unknown tongue edifieth himself, but he that prophesieth edifieth the church." Most translations have dropped the "unknown" because the Greek equivalent is NOT USED in the original manuscript. It was added by the KJV translators because they felt this particular tongue was not the same manifestation as described in Acts 2, where known languages were being spoken.
This verse is a gentle rebuke to those at Corinth who were trying to imitate the tongues that were truly a part of genuine Holy Spirit gifts. This is why Paul in the same sentence points them to the most needful gift of all for the church, the gift of prophesy. Prophesy was given so that all in the church might be edified.
This argument becomes even clearer in 14:6, "But now, brethren, if I come to you speaking with tongues, what shall I profit you unless I speak to you either by revelation, by knowledge, by prophesying or by teaching?" It is really not hard to understand Paul's point; If it is not instructive to the brethren then keep it to yourself. Even the gift of tongues that Paul shared was purposeful and not a mystery! It is important to remember that this entire chapter deals with the correcting of that which was wrong.
Now concerning the "tongues of angels", this appears in 1 Cor. 13:1, where Paul has begun his famous treatise on the value of all things being done in love as opposed to the selfish desire for attention and glory that some at Corinth were seeking. Here in verse one we read, "Though I speak with the tongues of men and of angels, but have not love, I have become sounding brass or clanging cymbal." Here Paul is giving a hypothetical example that those who had placed the actual gift on such a high pedestal could understand. The NKJV here begins with the word "though", but the Greek word that begins this statement is "ean" which clearly means "if". Again the translators of the KJV and NKJV both felt "though" was needed, but it decidedly changes the point of Paul. That point is "If I could speak in all the languages of men and angels." NOT THAT he did speak in the tongues of all men and angels! The context here is still meant to correct a vain and self-glorifying attitude that caused some to imitate the genuine languages that were actual tongues.
As for these tongues being a confirmation of one's salvation. We find on that day when the Apostles were filled with the Holy Spirit and spoke in about 15 different languages (Acts 2:8-11) that none of those three thousand who were baptized spoke in tongues. Nor did Simon the sorcerer who was baptized in Acts 8: 9-19 speak in tongues, in fact it isn't until verse 17 that the Apostles had to lay hands on these for them to receive any Holy Spirit gift. In fact the closest Scriptural example to this Pentecostal belief is found in Acts 10: 44-47 where we read, "While Peter was still speaking these words, the Holy Spirit fell upon all those who heard the word. And those of the circumcision who believed were astonished, as many as came with Peter, because the gift of the Holy Spirit had been poured out on the Gentiles also. For they heard them speak in tongues and magnify God. Then Peter answered, can anyone forbid water, that these should not be baptized who have received the Holy Spirit just as we have?"
Scripture tells us they had only "heard" the word, not yet believing. Peter states plainly, "Can anyone forbid water that these should not be baptized?" These Gentiles still need baptism to be forgiven of their sins. (Acts 2:38) Hence it is quite clear this singular manifestation of the Holy Spirit gift of the tongues was only a sign to Peter and the believers that God had approved the preaching of the Gospel message of salvation to the Gentiles. They had not been baptized, yet they still needed to be baptized. Thus this event never again duplicated in the NT Scriptures is simply a sign from God to Peter that he could continue and immerse them into Christ.
An accurate conclusion for all based on the Scriptural evidences is as follows: 1.) there is no such thing as a believer speaking in a "tongue of angels" or an "unknown tongue" and 2.) tongues are not a confirmation of salvation as some suggest Acts 10 states, instead it was a one time event meant as a sign to Peter. Further more as we concluded in part one of this teaching, tongues served their purpose a long time ago and as Paul sates in 1 Cor. 13:8, "whether there are tongues they will cease." Why did they cease? Because the time came that the last revelation of God to us had been dutifully recorded and preserved in a book we commonly know as the Bible.