To understand the purpose of tongues in the local church. This significance can be explored by understanding the purpose and use of tongues as used by Luke in the book of Acts.
Tongues: to speak with other than their native language, foreign language
2:3 glw~ssai (glōssai) 2:4, 2:11, 10:46 glw>ssaiv (glōssais)
Language: “the tongue or language peculiar to any people”
2:6, 2:8 diale>ktw (dialektō)
Speak/ Utterance: to speak out, but not normal speech, “but one belonging to dignified and elevated discourse” The word is only used in Acts, twice here with Peter and once in 26:25 with Paul to emphasize the sense of prophetic utterance. 2:4 ajpofqe>ggesqai (apophthegesthai) 2:14 ajpefqe>gxato (apephthegzato)
Acts 2 Pentecost
In Acts 2, Luke uses these two words (above) interchangeably to reference the same phenomenon. “In other NT literature the terms are likewise both used to mean ‘known language’ (cp. Acts 1:19; 22:2; 26:14 for examples of dialektos and Rev.7:9; 10:11; 11:9; 13:7; 14:6; 17:15 for examples of glossa)” All of the disciples were enabled to speak in other tongues/languages which allowed the crowd to hear the message in his own language (2:6-8). Their speech was intelligible and heard by each in own language. Luke, then, gives a long list of different nations and then records the crowd speaking of their hearing the language. Interesting to note is the parallel usage in verses 8 and 11. The significance of Luke’s parallel usage of these words seem to give the meaning that tongues are a type of foreign language, ie. dialect (known or unknown). In commentary on this passage Polhill adds, “the flow of the narrative does seem to favor the view of a miracle of foreign speech.”
Luke also uses the same word for the disciples speaking and Peter’s proclamation in verses 4 and 14. There is no indication that Peter spoke in tongues. It seems to be another indicator showing the speech is recognizable and understood by the people for the furtherance of the gospel message.
Most important to notice is the content of the “tongues/language.” Luke says they were “speaking of the mighty deeds of God.” Bruce adds, “The content is more important than the manner.” Peter continues to explain the “mighty deeds of God” by proclaiming the crucifixion and resurrection of Jesus Christ (v.22-24) and the fulfillment of God’s plan to pour out his Spirit on “all flesh” (v. 17). This also explains Luke’s list of nations foreshadowing the worldwide Christian mission.
Acts 10 “Gentile Pentecost” 
The entire account of Cornelius and Peter’s vision is quite fascinating. Luke is showing how the gospel message is expanding and uses Peter’s vision to show God’s call to take the gospel to the Gentiles. While Peter proclaims the gospel (v.34-43) the Holy Spirit fell upon Cornelius, “his relatives and close friends” (v.24), and they began to speak with tongues (glōssais) and exalt God (v.44). Polhill remarks that the Western text adds “έτέραις” for “other tongues/languages” to parallel Pentecost in Acts 2. Bruce cross-references Peter’s later commentary on the event in 11:15 and 15:8 to make the parallel stronger. One may ask, “Is this the same experience as that of Pentecost?” Williams appears to believe it is a different experience terming these tongues as “ecstatic utterance.” However, because of the strong parallels mentioned above, one can affirm that they are the same experience.
Also interesting to note is that Luke makes special mention that “all the circumcised believers” heard the Gentiles speak and were amazed (v.45-46). The reader can recognize the author’s use of tongues to mark the expansion of the gospel message (1:8), first in Jerusalem (ch.2), Samaria (ch.8, though no direct reference to tongues), and moving outward to the Gentiles in chapter 10 and beyond.
Acts 19 Ephesian Pentecost
As Paul journeyed through Ephesus he encountered some disciples who had not heard of the Holy Spirit and only had John’s baptism. In other words, they had no knowledge (or incomplete) of Jesus’ death, resurrection and ascension, or the events of Pentecost. Paul further explained the baptism of Jesus and they believed and were baptized. They also received the Holy Spirit and began speaking in tongues (glōssais) and prophesying. Again, Williams views this gift as parallel to that of 1 Corinthians 12 and 14 whereas, the text does not clearly indicate a manner of ecstatic speech. It can be seen that the author is further advancing the outline of the book, the spread of the gospel to all peoples.
Brief Summary/ Application
In the book of Acts, from these three passages, the gift of speaking in tongues/languages seems to be an indication of the spread of the gospel and the reception of God’s Holy Spirit. This gift also is understood to be speaking in foreign language(s) rather than unintelligible, ecstatic speech. Whether or not this gift is the same as that which Paul addresses in the Corinthian church (1Cor.12-14) is another question beyond the bounds of this paper. However, it seems they are different since in Acts they are known, intelligible languages, yet in 1 Corinthians Paul speaks of the gift needing interpretation for the edification of the church. If this understanding of the gift of tongues is correct, then the gift is certainly applicable today. However, one must remember that the content of the gift was primary over the manner in which the gift was used. The content was to speak the “mighty deeds of God” and to spread the gospel to other peoples. Unfortunately, this gift is not commonly used in this way but is more about human performance and human edification. In addition, to speak of the gift of tongues as normative and essential to Christian faith and worship practice seems to go beyond the scope of the book of Acts, and much more, Scripture as a whole.
The gift of tongues should not be used as a litmus test as to whether or not one is a Christian who has the Holy Spirit. In fact, the argument can be made from the book of Acts and the Bible as a whole that not every believer will speak in tongues. Key figures in the growth of the church from Acts are never recorded as having spoken in tongues. Such persons were Barnabas, Stephen, Philip, Mark, Silas, Timothy, Aquila & Priscilla, Apollos and not least to mention is the apostle Paul. It is known that Paul spoke in tongues (1 Cor 14:6, 14, 18). However, Paul makes it clear in the same letter that not all speak in tongues (1 Cor 12:30). From the list of key persons in Acts who were not recorded as speaking in tongues and Paul’s words to the Corinthians, it seems reasonable to conclude that the gift of tongues is not a gift of primacy or superiority but rather equal, if not in some sense lesser, to the other spiritual gifts.
In conclusion, Luke uses the reception of the Holy Spirit by believers as a developmental theme in the book of Acts. He is showing God’s sovereign plan to include the Gentile world in his salvation of the Jewish people. The gift of tongues in Acts was an indicator to the Jews that those believers had equally received the Spirit, as with their experience at Pentecost. As seen in Acts 2, 10 and in Acts 19, Jewish believers were the audience of God’s dispensing his Holy Spirit. It is essential to note that the gift of the Holy Spirit was given to empower believers to be God’s witnesses throughout the world (Acts 1:8). Churches and believers alike should focus on this latter purpose of the Holy Spirit rather than the minor gifts of the Holy Spirit.
 Paul expects a “no” answer from the question he poses. See Wayne Grudem, Systematic Theology: An Introduction to Biblical Doctrine (Grand Rapids, MI: Inter-Varsity Press, 1994), 1076.
 Joseph H. Thayer, A Greek-English Lexicon of the New Testament (Grand Rapids, MI: Baker Books, 1977), 118.
 Ibid., 139.
 Ibid, 69.
 David J. Williams, Acts, New International Biblical Commentary (Peabody, MA: Hendrickson Publishers, 1985), 49.
 Chad Brand, “Tongues, Gift of” in Holman Illustrated Bible Dictionary, ed. Chad Brand, Charles Draper and Archie England (Nashville: Holman Bible Publishers, 2003), 1605.
 Wayne Grudem, Systematic Theology (Grand Rapids: Inter-Varsity Press, 1994), 1072.
 John B. Polhill, Acts, The New American Commentary, Vol. 26 (Nashville, TN: Broadman, 1992), 100.
 F. F. Bruce, Commentary On the Book of Acts (Grand Rapids, MI: Eerdmans, 1954), 67.
 Ibid., 58.
 Polhill, 106.
 Ibid., 264. See also Bruce, 229 who also alludes to viewing this event as subordinate to Pentecost.
 Ibid., 263.
 Bruce, 229.
 Williams, 196.
 Bruce adds another parallel in that they both speak the “mighty deeds of God” and “magnify God” which is synonymous language, 230.
 Williams, 330.
 For fuller discussion see Paige Patterson, The Troubled Triumphant Church: An Exposition of First Corinthians, (Eugene, OR, 1983), 245-261.