Pentecost (meaning ″fifty″) was one of the three great festivals of Judaism, known as the Festival of Weeks in the Old Testament (Deuteronomy 16:9-12). It was celebrated 50 days after the beginning of barley harvest, a time to give thanks to God for the completion of the harvest. Later, it came to commemorate the giving of the law to Moses at Mount Sinai (Exodus 19:1). The festival was all about fulfilment, completion, and finality. It is most fitting then that the Holy Spirit should be poured out on the church at this festival. His coming is the evidence that Christ has risen and ascended to God's right hand; His work is now complete.

The coming of the Spirit is associated with the sound of wind (v. 2; cf. John 3:8) and the sight of fire (v. 3; cf. Exodus 3:2). The effect is that the 120 gathered disciples were filled with the Holy Spirit (v. 4; see Jeremiah 31:33, which anticipates this day) and they speak in tongues, so that the different language groups in the crowd (vv. 9-11) hear them disclosing the wonders of God in their own language. Luke records the range of responses-″bewilderment″ (v. 6), ″utterly amazed″ (v. 7), ″amazed and perplexed″ (v. 12), and mockery (v. 13).

We may argue about tongues here, but note that the recipients did not speak in inarticulate sounds. The word ″language″ in verse 6 translates the original word ″dialect″ and parallels with verses 4 and 11 where the word used is glossa, or tongue. The ideas are parallel and the words are used synonymously-the ″tongue″ here is a dialect; here are people speaking in known native languages and dialects without having attended language school.

The focus of these verses is that God has come to live among His people, and according to some commentaries, the immediate effect of this is the reversal of the scrambling of languages that occurred with the building of the Tower of Babel (Genesis 11). The Holy Spirit has come upon the church and He enables effective witness. He is the Spirit who Jesus said would empower believers for witness (Acts 1:8).

Matthew Henry says the significance of this event ″is to dignify and so to distinguish these men as messengers from heaven and therefore like Moses at the bush, the crowd will turn aside and see this great sight″.³

³Henry, Commentary on the Whole Bible.