In Acts 19, we see that Apollos and some Ephesians became followers of John the Baptist and received his baptism. They knew that John pointed beyond himself to Jesus. They probably knew not only of Jesus’ life and ministry, but also about his death and resurrection. D.A. Carson writes: But apparently they knew nothing of Pentecost and what it signified of eschatological transformation. This ignorance could have developed because they (or the people who taught them) left Jerusalem (like tens of thousands of other diaspora Jews) shortly after the Passover feast—that is, they learned of Jesus’ death and resurrection, but not of the coming of the Spirit. (Showing the Spirit) These people were in a salvation history time-warp. They are in the same situation as the believers of Acts 1. They are living in the section of time before the unfolding of salvation history. This is a unique experience because it is rather abnormal to find someone who follows John the Baptist’s teaching of Jesus, accepts Jesus’ life, death, and resurrection as true, and is ignorant of Pentecost. The tongues of Acts 19 do not serve as communication of glorious praise as in Acts 2, and they are not to authenticate a new group to the Jerusalem church. Rather, they serve as the attestation to the Ephesian believers themselves of the gift of the Spirit that transfers them as a group from the old era to the one in which they should be living (D.A. Carson, Showing the Spirit).