A few weeks back, I explained how different camps of Christians (be they Catholics, Pentecostals, or Reformed folks) each had a different perspective on what was going on in Acts 8 with the obvious manifestation of the Holy Spirit in the lives of new believers. I left with a question about the 8th chapter of Acts: 'To what extent was the Spirit of God manifesting itself in Acts 8?' I noted that there definitely seems to be a connection between Acts 2 and Acts 8.
One argument is to suggest that these Samaritan people had not become Christians until they received the Spirit from the Apostles who came from Jerusalem. This probably isn’t correct because we see Philip baptizing these same people and he would not have done that had he not been convinced of their conversion (prior to the arrival of the Apostles from Jerusalem).
Acts 8:14-16 says this:
14 Now when the apostles at Jerusalem heard that Samaria had received the word of God, they sent to them Peter and John, 15 who came down and prayed for them that they might receive the Holy Spirit, 16 for he had not yet fallen on any of them, but they had only been baptized in the name of the Lord Jesus. (ESV)
A major key to understanding what is going on here is found in the phrase “fallen on” (see v. 16), which is an English translation of the Greek word pronounced ‘epi-peptokos’. This word (or a variation of it) is commonly used by Luke in both his gospel and the book of Acts. It is used, for example, in Luke 15 in Jesus’ parable of the prodigal son:
20 And he arose and came to his father. But while he was still a long way off, his father saw him and felt compassion, and ran and embraced him and kissed him. (ESV)
The English word ‘embraced’ comes from the Greek word pronounced 'epi-pesen', a variation of epi-pepto in that the word ‘embraced’ could be taken to mean ‘fall over upon’. (A good visual illustration of this is found in Rembrandt's painting The Return of the Prodigal Son)
Just as we see the Holy Spirit falling upon the Samaritan believers, we will see the same thing happen to Gentiles in Acts 10:44-45 in the house of Cornelius:
44 While Peter was still saying these things, the Holy Spirit fell on all who heard the word. 45 And the believers from among the circumcised who had come with Peter were amazed, because the gift of the Holy Spirit was poured out even on the Gentiles. (ESV)
What I think we are seeing with the Holy Spirit falling upon the Samaritans in Acts 8 and falling upon the Gentiles in Cornelius’ house in Acts 10 are two additional Pentecost experiences that echo back to the Day of Pentecost as described in Acts 2. The Acts 2 experience was for the Jews who had placed their faith in Jesus. The Acts 8 experience was for the Samaritans who had placed their faith in Jesus. The Acts 10 experience was for the Gentiles who had placed their faith in Jesus. Meanwhile, both the Acts 8 and Acts 10 experiences (which, as described, had a form of visual or audible verification) were for the Jews to observe and recognize as taking place in people who were not of a Jewish background. In other words, what the Spirit was doing in the lives of these non-Jewish believers is also meant to be seen by those Jewish followers of Christ so that they might see how God was now reaching people beyond just the children of Jacob. The good news of the gospel was going out to those beyond just the house of Israel to fulfill what was promised that Israel would indeed be a light to the Gentiles  and that, through Abraham’s offspring, all nations would be blessed .
 Isaiah 49:6 6 and He said: ‘It is a light thing that Thou shouldest be My servant to raise up the tribes of Jacob and to restore the preserved of Israel. I will also give Thee for a light to the Gentiles, that Thou mayest be My salvation unto the end of the earth.’”
 Genesis 12:1-3 1 Now the Lord had said unto Abram, “Get thee out of thy country, and from thy kindred and from thy father’s house, unto a land that I will show thee. 2 And I will make of thee a great nation, and I will bless thee and make thy name great; and thou shalt be a blessing. 3 And I will bless them that bless thee, and curse him that curseth thee; and in thee shall all families of the earth be blessed.”