The immediate effect of the coming of the Holy Spirit upon the disciples was not so much an enduement of power for healing the sick, but rather of boldness and power to speak forth as Christ’s witnesses. Prior to the coming of the Holy Spirit upon the disciples in Acts 2, Jesus had already given them a measure of his authority to heal the sick and cast out demons for the purpose of preaching the kingdom of God. Even in the gospels, the disciples were doing miraculous healings to confirm that Jesus was the Messiah.
Luke 9:1 When Jesus had called the Twelve together, he gave them power and authority to drive out all demons and to cure diseases, 2 and he sent them out to preach the kingdom of God and to heal the sick.
Luke 10:1 After this the Lord appointed seventy others and sent them two by two ahead of him to every town and place where he was about to go. …9 “Heal the sick who are there and tell them, ‘The kingdom of God is near you.’”
Of course it is likely that their effectiveness in healing the sick increased after the coming of the Spirit, but this was not His primary purpose. What does the Scripture say in Acts?
Acts 1:8 “But you will receive power when the Holy Spirit comes on you; and you will be my witnesses in Jerusalem, and in all Judea and Samaria, and to the ends of the earth.”
They were to receive power to be witnesses for Jesus Christ when the Holy Spirit came upon them. By definition a witness testifies or speaks on behalf of someone else. In a court of law, for example, the witness speaks on behalf of the defense or the prosecution. The primary function of a witness in Acts is to speak on behalf of the One who sends us, Jesus Christ.
Acts 2:1 When the day of Pentecost came, they were all together in one place. 2 Suddenly a sound like the blowing of a violent wind came from heaven and filled the whole house where they were sitting. 3 They saw what seemed to be tongues of fire that separated and came to rest on each of them. 4 All of them were filled with the Holy Spirit and began to speak in other tongues as the Spirit enabled them.
After the Spirit came upon the disciples on the Day of Pentecost, they first began to speak in other tongues. What were they speaking?
5 Now there were staying in Jerusalem God-fearing Jews from every nation under heaven. 6 When they heard this sound, a crowd came together in bewilderment, because each one heard them speaking in his own language. ….11 ….we hear them declaring the wonders of God in our own tongues!”
They were boldly and openly praising God before a crowd of unbelieving Jews, quite a contrast from their timid behavior just a few days earlier after the crucifixion when they were in hiding. They were speaking forth boldly for God.
12 Amazed and perplexed, they asked one another, “What does this mean?” 13 Some, however, made fun of them and said, “They have had too much wine.” 14 Then Peter stood up with the Eleven, raised his voice and addressed the crowd: …….
Peter, the one who denied Jesus three times several days earlier in fear of losing his life, steps forward before a crowd of thousands and speaks with uncharacteristic and unusual boldness.
37 When the people heard this, they were cut to the heart and said to Peter and the other apostles, “Brothers, what shall we do?” 38 Peter replied, “Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of your sins. 40 With many other words he warned them; and he pleaded with them, “Save yourselves from this corrupt generation.” 41 Those who accepted his message were baptized, and about three thousand were added to their number that day.
The words Peter spoke were powerful—anointed by the Holy Spirit—and convicted the listeners. Some days later, Peter again speaks forth with great power and boldness, this time to a beggar who was hopelessly crippled since birth. Because of this the lame man was healed, resulting in the salvation of many souls.
It is reasonable to conclude that the immediate effect of the Spirit’s coming upon the disciples was not so much simply the power to heal the sick, but rather power and boldness to speak forth in connection with sharing the gospel of Christ, whether to unbelievers or to infirmities or to whatever the situation demanded. The very first manifestation of the Spirit’s coming was not a miraculous healing, but boldness to declare the wonders of God and to witness about Jesus Christ.