Some believers have misread Acts 19:1-7 to imply that there were believers that had not received the Holy Spirit yet but later on in life, but these "certain" disciples were disciples of John the Baptist's. That means there were still disciples of John the Baptist's after His resurrection and ascension that did not believe in Jesus Christ as their Saviour yet. To set precedent for this reading, we go to the event before that one in Acts 18:24-27. Acts 18: 24 And a certain Jew named Apollos, born at Alexandria, an eloquent man, and mighty in the scriptures, came to Ephesus. 25 This man was instructed in the way of the Lord; and being fervent in the spirit, he spake and taught diligently the things of the Lord, knowing only the baptism of John. So this Jew named Apollos knew only the baptism of John the Baptist's. 26 And he began to speak boldly in the synagogue: whom when Aquila and Priscilla had heard, they took him unto them, and expounded unto him the way of God more perfectly. It was after Aquilla and Priscilla that Apollos believed in Jesus Christ to be received by the disciples, because after having been converted, Apollos helped the disciples much in the scripture. 27 And when he was disposed to pass into Achaia, the brethren wrote, exhorting the disciples to receive him: who, when he was come, helped them much which had believed through grace: And so we go to the next event; Acts 19:1 And it came to pass, that, while Apollos was at Corinth, Paul having passed through the upper coasts came to Ephesus: and finding certain disciples, Paul came across people that were obviously some kind of disciples, and not knowing what kind, he had asked this question below. 2 He said unto them, Have ye received the Holy Ghost since ye believed? And they said unto him, We have not so much as heard whether there be any Holy Ghost. Puzzled over what kind of disciples that they were, Paul had asked this question below. 3 And he said unto them, Unto what then were ye baptized? And they said, Unto John's baptism. So the answer by what water baptism they were under, told Paul what kind of disciples they were; John the Baptist's disciples. It was then Paul told the disciples of John the Baptist's about Jesus Christ. 4 Then said Paul, John verily baptized with the baptism of repentance, saying unto the people, that they should believe on him which should come after him, that is, on Christ Jesus. And so these disciples believed on Jesus Christ to be water baptized in His name. 5 When they heard this, they were baptized in the name of the Lord Jesus. 6 And when Paul had laid his hands upon them, the Holy Ghost came on them; and they spake with tongues, and prophesied. 7 And all the men were about twelve. So those certain disciples of John the Baptist's were never believers in Jesus Christ, and that was why they had not received the promise of the Holy Ghost, but now they are believers in Jesus Christ, and by having received the Holy Ghost, they are saved.