2:1. The day of Pentecost was an annual feast that followed the Feast of Firstfruits by a week of weeks (i.e., seven weeks, or 49 days) and therefore also was called the Feast of Weeks (cf. Lev. 23:15–22). The name “Pentecost,” of Greek derivation, means 50 because it was the 50th day after the Firstfruits feast (Lev. 23:16).
2:2–3. The references to “wind” and “fire” are significant. The word for “Spirit” (pneuma) is related to pnoe, the word translated “wind” here. It also means breath. Both nouns—“spirit” and “wind” or “breath”—are from the verb pneō, “to blow, to breathe.” The sound like the blowing of a violent wind … from heaven points to the power of the Holy Spirit and the fullness of His coming.
The tongues of fire portray the presence of God. Several times in the Old Testament God displayed Himself in the form of flames (Gen. 15:17; Ex. 3:2–6; 13:21–22; 19:18; 40:38; cf. Matt. 3:11; Luke 3:16).
No believer there was exempt from this experience, for the flames separated and came to rest on each of them.
2:4. The filling with the Holy Spirit is separate from the baptism of the Spirit. The Spirit’s baptism occurs once for each believer at the moment of salvation (cf. 11:15–16; Rom. 6:3; 1 Cor. 12:13; Col. 2:12), but the Spirit’s filling may occur not only at salvation but also on a number of occasions after salvation (Acts 4:8, 31; 6:3, 5; 7:55; 9:17; 13:9, 52).
An evidence of the baptism of the Holy Spirit was other tongues (heterais glōssais; cf. 11:15–16). These were undoubtedly spoken living languages; the word used in 2:6, 8 is dialektō, which means “language” and not ecstatic utterance. This gives insight into what is meant by “tongues” in chapters 2; 10; 19; and in 1 Corinthians 12–14.
This event marked the beginning of the church. Up to this point the church was anticipated (Matt. 16:18). The church is constituted a body by means of Spirit baptism (1 Cor. 12:13). The first occurrence of the baptism of the Spirit therefore must indicate the inauguration of the church. Of course Acts 2:1–4 does not state that Spirit baptism took place at Pentecost. However, 1:5 anticipates it and 11:15–16 refers back to it as having occurred at Pentecost. The church, therefore, came into existence then.