Final answer:
Enns highlights that during Pentecost in the book of Acts, the Holy Spirit empowered the Apostles to speak in different languages, symbolizing the universality of the Christian message.
Step-by-step explanation:
According to Enns, the Spirit's empowerment to speak in tongues in the book of Acts included the miraculous ability for the Apostles to preach the crucified and risen Christ in different languages so that people of various 'tribes' and 'tongues' could understand. This event is commemorated by the Pentecost, which took place fifty days after Easter and is marked by the Holy Spirit descending upon the Apostles in the form of tongues of fire. This empowered the Apostles to communicate effectively across linguistic barriers, symbolizing the universality of the Christian message.