Hearing that certain converts in "Samaria had received the word of God (Acts 8:14)", Peter and John went and "prayed for them (Acts 8:15)." Paul also went to Ephesus and found "certain disciples (Acts 19:1)." These apostles wanted to make sure that the new believers received the Holy Spirit. Paul "said unto them, Have ye received the Holy Ghost since ye believed (Acts 19:2)?" When they replied that they had "not so much as heard whether there be any Holy Ghost", Paul asked them, "Unto what then were ye baptized (Acts 19:2,3)?"
People are water baptized into the truth they receive. A disciple, then, is a follower of the truth he has learned because he has to "bear his cross (Luke 14:27)" in order to follow Jesus. The new disciples replied that they had been baptized "unto John's baptism (Acts 19:3)" with the baptism of repentance (Acts 19:4)." The truth they had been baptized with was like that of Apollos' teaching. He "taught diligently the things of the Lord, knowing only the baptism of John (Acts 18:25)" which was "that [people] should believe on him [Jesus] which should come after him [John] (Acts 19:4)." But when Aquila and Priscilla took Apollos and "expounded unto him the way of God more perfectly (Acts 18:26)", showing that "Jesus was Christ (Acts 18:28)", Apollos received the complete gospel. Thus the new converts "were baptized in the name of the Lord Jesus (Acts 19:5)."
Peter and John discovered that the Samaritans, too, were "baptized in the name of the Lord Jesus (Acts 8:16)" but that the Holy Ghost "was fallen upon none of them (v.16)." We know that we become "sons of God" when we believe "on his name (John 1:12)." But where is the Holy Spirit at salvation such that He might have "fallen upon" us? In the Scriptures we see that:
Thus, we conclude that we are saved when we believe with the faith we receive by grace from God. Furthermore:
Therefore, since Jesus had been glorified, the disciples properly received the Holy Spirit because they were recognized as believers. Finally:
When you believe, you are sealed with the Holy Spirit. So it is simply by the exercise of faith (nos. 1-3) that you receive (nos. 4-5) the Holy Spirit in your heart (nos. 6-7). Therefore, we have the Holy Spirit within us when we are saved through belief in the Lord Jesus Christ.
So when Peter and John prayed for the Samaritans that "they might receive the Holy Ghost (Acts 8:15)", they were expecting another anointing of the Holy Spirit. When they laid hands upon the believers, "they received the Holy Ghost (Acts 8:17)" just as "when Paul had laid hands upon them, the Holy Ghost came on (Acts 19:6)" the Ephesians. Scripture doesn't require that hands be laid on a person for him to be saved, but "Simon saw that through laying on of the apostles' hands the Holy Ghost was given (Acts 8:18)." This shows that Passover and Pentecost are separate New Testament experiences.
A distinction is also seen in the feasts concerning leaven. At Passover "shall there be no leaven found in [the] houses (Exodus 12:19)." Whereas at Pentecost "two wave loaves...shall be baken with leaven (Leviticus 23:17)." However, both feasts have in common the requirement to "be filled with the Spirit (Ephesians 5:18)" by "singing with grace in your hearts to the Lord (Colosians 3:16)." But with the baptism of the Holy Spirit there is a step of faith involved, for "how much more shall your heavenly Father give the Holy Spirit to them that ask him (Luke 11:13)?"