Gift of Tongues
What this gift actually was has been a subject of much discussion. Some have argued that it was merely an outward sign of the presence of the Holy Spirit among the disciples, typifying his manifold gifts, and showing that salvation was to be extended to all nations. But the words of Luke (Acts 2:9) clearly show that the various peoples in Jerusalem at the time of Pentecost did really hear themselves addressed in their own special language with which they were naturally acquainted (compare Joel 2:28-29).
Among the gifts of the Spirit the apostle enumerates in 1 Corinthians 12:10-14:30, “divers kinds of tongues” and the “interpretation of tongues.” This “gift” was a different manifestation of the Spirit from that on Pentecost, although it resembled it in many particulars. Tongues were to be “a sign to them that believe not.”