Union with God
As a result of the Spirit's descent, we are no longer separated from God. Sure, in Christ, humanity and divinity are forever united. And to be clear, the Incarnation has made possible our re-union with God. But as individuals, we are isolated from God until his Spirit penetrates our lives and takes residence in our hearts. As New Testament scholar James D. G. Dunn explains, "In one sense, therefore, Pentecost can never be repeated—the new age is here, and cannot be ushered in again. But in another sense . . . the experience of Pentecost can and must be repeated in the experience of all who would become Christians." Apart from the descent of the Spirit into our own lives, we are dead branches disconnected from the living vine.
On Pentecost, the church was born. A Spirit-filled community was established. A body of believers was inextricably fixed to Christ the head. And this happened at both the individual and corporate levels. Paul tells us that God "saved us through the washing of rebirth and renewal by the Holy Spirit, whom he poured out on us generously through Jesus Christ our Savior, so that, having been justified by his grace, we might become heirs having the hope of eternal life" (Titus 3:5–7). Through the mighty work of his Spirit, God has cleansed us from sin and given us new life. We are justified, considered holy in his sight. And because the Spirit lives in us, we belong to Christ—are made members of his body—and have become children of God (Rom. 8:9, 14–17).
And this is totally God's doing. As Bible scholar Frederick Dale Bruner explains, "Rather than pointing to the fulfillment of any or several spiritual requirements—for instance, 'when the disciples had fully met the price of Pentecost'—Luke points to history and to the sovereign timing of God." God is the sole initiator of salvation, and he pours out his Spirit unconditionally and without our solicitation. God is the subject and we are the direct object. He breaks down the barrier that sin erected between us and him, and he fills us with his life-giving Spirit, making us his people.
Union with Others
But that's not all. The Spirit's descent also breached the barrier that separated us from one another. Acts tells us that "Jews from every nation under heaven" were gathered in Jerusalem. "Parthians, Medes and Elamites; residents of Mesopotamia, Judea and Cappadocia, Pontus and Asia, Phrygia and Pamphylia, Egypt and the parts of Libya near Cyrene; visitors from Rome (both Jews and converts to Judaism); Cretans and Arabs" (2:9–11)—all these people heard the gospel, through tongues of fire and Peter's preaching. It was a sort of reversal of Babel. And 3,000 of them became Christians.
These weren't Jews only. Luke says the visitors from Rome we both "Jews and converts to Judaism"—meaning some were Gentiles. As minor as the detail might seem, it sets the trajectory for the rest of Luke's book. Later in Acts, we see the gospel moving from Jerusalem to other nations, and eventually Paul's ministry to the Gentiles becomes Luke's sole focus.