In the first half of Acts 19, Luke uses the phrase “kingdom of God” to describe Paul’s preaching and the subject of his persuasions in Ephesus. This phrase is infrequent in the book of Acts. Prior to Acts 19, Luke had only used the phrase four times; after this text, he uses it again in the context of Paul’s farewell speech to the Ephesian elders in Acts 20 and then as a capstone to Paul’s efforts while a prisoner in Rome in Acts 28.
Now, there is nothing inherently special about this phrase. It is simply another way to describe the good news of the grace of the Lord Jesus. And yet, it is another helpful way to understand Acts 19. Therefore, I will use this reflection to develop the thought further as it pertains to Paul’s Ephesian ministry.
To begin, we need to realize that the kingdom of God has more than one sense to it. Maybe most of us think about a specific location with specific geography boundaries, and perhaps that’s the case because there are few absolute monarchies in existence these days. But a kingdom can also be a reference to the rule and authority that a monarch exercises. Of course, these two senses are interconnected because rule and authority cannot be exercised without a location to exercise it.
With that said, Geerhardus Vos develops the idea of the kingdom of God in a helpful way that aligns well with the activity described by Luke while Paul is in Ephesus. To begin, Vos mentions that the kingdom of God is a sphere of divine power. “The source of this kingdom-power is according to our Lord’s teaching the Spirit.” This is precisely what we see in the baptisms at the beginning of Acts 19. This Ephesian Pentecost, so closely tied with Paul’s teaching that the fullness of the gospel promises, to which John the Baptist looked, had come with the person and work of Jesus Christ. For these disciples who were awaiting the promised kingdom of God, the gifts of the Holy Spirit were proof enough that the fullness of those promises had come.
Beyond that, Luke describes in this chapter a number of extraordinary miracles that were performed through the hands of Paul. Paralleling the miracles of Jesus, these things also testify to the presence of the kingdom of God. “It is a mistake to think that Jesus looked upon [his miracles] exclusively as signs authenticating his mission. … [T]hey are signs in a different sense, viz., signs of the actual arrival of the kingdom, because they show that the royal power of God is already in motion.” As it was with Jesus, so it is with Paul in Ephesus and Asia. These extraordinary miracles point to the fullness of the kingdom power that has come with the proclamation of the name of Jesus.
But the royal power that was evident in the Spirit’s outpouring and Paul’s miracle-working was not for show but for good. The kingdom of God is a sphere of divine blessing just as it is a sphere of divine power. Vos notes that kingdom blessing comes in both positive and negative qualities. For the positive blessings, Vos speaks primarily of spiritual blessings, the “spiritual growth and activity” of believers that flows from our communion with God and union with Christ. However, we should not overlook the material blessings that are evident in Paul’s miracles as the sick are physically healed, and that by the power of God rather than Paul.
“Negatively, the kingdom includes the deliverance from all evil.” In our text, the baptisms correspond to this negative blessing in that they are a sign and seal of the washing away of corruption, the forgiveness of sins. Moreover, Luke explicitly notes that Paul’s miracles included the casting out of demons.
Finally, and related, “righteousness is one of the blessings to be bestowed in the kingdom.” To be sure, that blessing begins with God’s righteousness imputed to us, but it continues with the sanctifying work of the Spirit in our lives. That sanctifying work, the blessing of righteousness and being made fit for heaven, is evident in the public book burning in Acts 19. Those who had been sanctified by the blood of the cross continued to be sanctified as they grasped the seriousness of their sin and the satisfaction of aligning their wills with God’s.
In sum, as the kingdom of God comes to bear on the kingdom of this world, royal power issues in royal blessing, including royal righteousness both imputed and experienced. Such was the experience of Ephesus while Paul was there, and such is our experience while we await the fullness of the kingdom in the future.
 Herman Ridderbos, The Coming of the Kingdom, ed. Raymond Zorn, trans. H de Jongste (Philadelphia: P&R Publishing, 1962), 24–25; Geerhardus Vos, The Teaching of Jesus Concerning the Kingdom of God and the Church (Phillipsburg: P&R Publishing, 1972), 21.  Vos, Kingdom, 56.  Vos, Kingdom, 54.  Vos, Kingdom, 75.  Vos, Kingdom, 72.  Vos, Kingdom, 64.