What would have happened to the Church if the Holy Spirit had not come to the apostles on the Day of the Pentecost?

A:The Holy Spirit is reported in Acts 2:1-4 as coming to the apostles some forty days after the Resurrection of Jesus, on the Day of Pentecost, as tongues of flame. A little-known account in John's Gospel (John 20:22) also has the disciples receiving the Holy Spirit when Jesus breathed on them, on the same day as the Resurrection.

Had the author of Acts not reported the disciples receiving the Holy Spirit on the Day of Pentecost, no doubt the parallel account in John's Gospel would have received greater prominence, with the Church proceeding much as it did.