Many Pentecostal Christians today claim to speak in tongues. Some claim to be speaking in some actual human language other than their own, while others claim to be speaking an unknown tongue, or a language of angels – not a human language found on earth.
However, the gift of tongues is no longer used today. It was used in the days of the apostles to preach and convert unbelievers because it was used as a sign.
Acts 2 is a wonderful chapter for understanding the purpose of speaking in tongues. It begins with the disciples receiving the Holy Spirit. In verses 5-11, the apostles begin speaking in tongues to a large crowd. The rest of the chapter continues with Peter speaking about the repentance of sins and the fulfillment of prophesy, and toward the end, verse 41, we see that 3,000 were converted and baptized as a result of hearing the message in their own language.
From this passage, we can clearly see that the purpose of speaking in tongues was to preach and spread the gospel message. To further emphasize this point, we have 1 Corinthians 14:22, which says that the gift of tongues is meant as a sign for unbelievers, showing that it was supposed to be used as a method of proving the truth of the Gospel to those who had not yet received it.
Matthew 12:38, 1 Corinthians 1:22, and John 6:30 are examples of scriptures that show that the Jews needed signs in order to believe. And as we showed in 1 Corinthians 14:22, the purpose of speaking in tongues was to be one such sign so that the unbelievers would believe (And Acts 2:41 shows one instance where 3,000 were converted through it). But John 20:30-31 reads, "Jesus performed many other signs in the presence of his disciples, which are not recorded in this book. But these are written that you may believe that Jesus is the Messiah, the Son of God, and that by believing you may have life in his name." In the time of Jesus, there was no New Testament, as it was still being written. All that the people had were the Old Testament Scriptures, and their eyes had to be opened to understand the prophesies pointing to Jesus. So they depended on these signs and miracles of Jesus to prove that He was indeed God's son. However, this scripture in John indicates that the New Testament was written so that we can believe (exactly the same outcome as seeing the signs such as speaking in tongues), which would mean that we no longer need to depend on these signs and wonders. Thus, the gift of speaking in tongues, along with the other miraculous signs, died with the apostles.
Another way to show this is in 1 Corinthians 13:8-12. Verse 8 says that prophesies and knowledge will fail, but that tongues will cease. It explains in the next two verses that with both prophesies and knowledge, we only know and understand very minimally as imperfect human beings. However, when we do reach perfection at the end of our earthly life, we will no longer have any use for partial knowledge. However, with tongues, it just says they will cease or come to an end. It continues by saying, "When I was a child, I spake as a child, I understood as a child, I thought as a child; but when I became a man, I put away childish things," comparing the church through the ages as a child growing in maturity. At the beginning, the people needed "childish things," such as signs and wonders, to get established. But once it had the New Testament scriptures to study from, they no longer needed the signs and wonders, so they "put away childish things," showing that speaking in tongues and other miracles were no longer in use.
To conclude, the purpose of speaking in tongues was to be a sign to the unbelievers and no, speaking in tongues is no longer happening today. It has not been in place since the days of the apostles, before the New Testament was completed.