Understanding this historical transition of the Holy Spirit's ministry from being focused on the nation of Israel to the whole world is critical for understanding the rest of the New Testament. The Spirit's coming brought new and additional revelation for the new era that was beginning, known as the Church Age.
The Holy Spirit's ministry to the different groups was made evident by signs, miracles, and the ability to speak in different languages. The Spirit ministered through the apostles to the Samaritans, the Gentiles, the disciples of John the Baptist, as well as to the Jews. As a result, all four groups were solidified by the teaching of the apostles, under one Spirit's ministry, thus unifying the Church.