What is speaking in tongues in the Bible? Are there multiple different kinds? Is it speaking in all understandable languages at once, or is it speaking unknown languages? Is it an art form? Babbling like an infant? An expression of worship?
The word “tongue” has, as its primary meaning, that thing in your mouth that makes it possible, among other things, to articulate a language. Since the tongue is essential for speaking, especially speaking clearly (1 Corinthians 14:8-9), it came to be used to mean a language, as when a person speaks his or her “mother tongue.” One can verify that “tongue,” in the Bible, means an established language by the context in which the term occurs. For example, in Genesis 11:7 God talks about going down to those building the tower of Babel in order to confuse their “tongue” (Greek OT; Hebrew has “lip,” meaning speech, see Gen 11:1).
Acts 2:4-21 records how the apostles spoke in the native languages of the devout Jews who came to Jerusalem from every nation under heaven, speaking in these languages (tongues, verse 4, 11), as the Holy Spirit made them able. The purpose of God granting the apostles this ability on this occasion was not in order to communicate with these devout Jews, since the apostles could have spoken to them in Greek, Hebrew, or likely also Aramaic. The point of speaking to them in the languages of these foreign nations (listed in verses 9-11) was to prove at least two things; one, God’s redemptive work was accomplished in Christ for ALL people and, two, that God’s redemptive work is accomplished immediately by means of His Word (see Peter’s use of this argument in Acts 11 and 15, in reference to his visit to Cornelius’ house).
If one studies the occurrence of these special manifestations of the Holy Spirit in Acts, what we notice is that such special manifestations always come by way of the apostles (or the laying on of their hands) and include the “falling of” the Holy Spirit in order to make irrefutable confirmation of the grace of God accomplishing redemption in the presence of Jewish opposition (Acts 2, 10 (11 and 15 by reference)) or in order to prevent any future question about the certainty of God’s redemptive work (Acts 19). On other occasions, when there is no one present to contest or oppose the working of God’s Word, there is no laying on of hands, no special manifestation of the Holy Spirit, and no speaking in a foreign language, as in the case of Philip and the Ethiopian Eunuch (Acts 8) or the Philippian jailer and his family (Acts 16). Paul devouts much of 1 Corinthians 12-14 to addressing their misunderstanding about speaking in tongues/languages. Chapter 14 especially is difficult to understand without a slow and careful reading.