PENTECOST 33 C.E. was an outstanding date in human history. On that day the Christian congregation was founded by the outpouring of God’s holy spirit upon about 120 of Jesus’ disciples assembled in an upper room in Jerusalem. The Bible relates that, as a result of this, “they all became filled with holy spirit and started to speak with different tongues.”​—Acts 2:4.

This ‘speaking in tongues’ was no outflow of gibberish from persons in religious ecstasy. Foreigners present understood what was said and were astonished, asking: “How is it we are hearing, each one of us, his own language in which we were born? . . . we hear them speaking in our tongues about the magnificent things of God.”​—Acts 2:8, 11.

The apostle Peter, according to Acts 2:14-21, explained that speaking in tongues on that occasion signified that God’s holy spirit had been poured out upon those Christian disciples in fulfillment of Joel 2:28-32.

Christians at Pentecost spoke in tongues about “the magnificent things of God.” (Acts 2:11) The Expositor’s Greek Testament points out that the Greek word for “magnificent things” is used “not only of the Resurrection of the Lord . . . , but of all that the prophets had foretold, of all that Christ had done and the Holy Ghost had conferred.”

In other words, speaking in tongues among Christians originally served to edify the listeners with information about God’s purpose in connection with Jesus Christ. In harmony with this, the apostle Paul directed that all speaking in tongues be translated, “that the congregation may receive upbuilding.” (1 Cor. 14:5, 27, 28)