Commenting on Acts 19.8, William Baird wrote, “In Acts the kingdom of God seems similar to the church (cf. 8:12), but the idea of God’s rule to be consummated in the future is not lacking (cf. 14:22)” IOVC. Indeed it does seems similar, since the church is the present earthly manifestation of the kingdom.
And Paul preached this kingdom. “So Paul entered the synagogue and spoke out fearlessly for three months, addressing and convincing them about the kingdom of God” Acts 8.12.
The Way and the disciples are mentioned in the following verse, both referring to the church, reinforcing the inclusion of the people of God as part of his message. The referrent of the Way is “the early Christian movement” NNIBD; the “teaching and manner of life relating to Jesus Christ” BGAD; “the way of the Christian faith” Mounce.
There is simply no way to separate the message from the messengers, the Christ from the body, the kingdom from the people over whom God reigns.
And those who refuse to explain to the lost who these people are, distinct from the false religions that exist, including those that call themselves Christians but are not, fail to do their duty of proclaiming the gospel of Christ.