as i was examining the book of acts and the work of the Holy Ghost we see how He enabled the disciples to speak words that had no origin in the human mind but they were speaking as the Holy Ghost was leading.
first off, prior to the coming of the Holy Spirit upon the disciples the apostle peter was were weak (when they could not keep watch and pray with Jesus), showed a lot of cowardice (when he denied the Lord Jesus)and anger ( when Jesus was arrested Peter wanted to kill the soldier with the sword).
so we see in chapter 2 when the Spirit comes at Pentecost, they just started to speak in tongues, people would come and witness the outpouring of the Holy Spirit and His work in the disciples, some thought they were drunk but we see how peter spoke to all these people and they were amazed by the way he was addressing the crowd, with great authority and at the end of chapter 3 about 3 thousand individuals gave their lives to Christ due to the work of the Holy Spirit.
so i think that if the Holy Spirit had not come at the day of Pentecost none of this would have happened, no soul would have been saved that day and of course peter would not have been able to say a thing, he was so bold that he was not afraid of dying for the Lord.
second off, in chapter 6 we see the story of Stephen, a man full of the Holy Spirit was chosen and began his ministry, the bible tells us that he performed miracles and wonders, however opposition arose and got seized by the members of the synagogue so when they were accusing him the men sitting in the Sanhedrin looked a Stephen and they saw the face like the face of an angel and they could not understand by what spirit he was speaking, they could not stand against such a wisdom.
so the Spirit enables Stephen to give one of the most remarkable speeches in the bible, the speech at the Sanhedrin.
soon after, they were furious, they looked at him and his face, once again, was like the face of an angel, he looks up to heaven and sees heaven open, the glory of God and the Son of Man standing at the right hand of God in power.
so they got so mad at him that started to stone him, so he commits his spirit into the hands of God and even prayed for his aggressors" Lord please do not hold this sin against them" and when he had said that he fell asleep...
what a testimony of the power of the Holy Spirit in the life of a believer, we can love when He is in us, we can forgive when He is in us, we can lay down our lives for God boldly when He is in us, perhaps if i had been he i would have fought back, i would have taken down my aggressors... this is definitely one of the things i need to work on, sometimes i wonder how i would react if someone broke in my house and try to rape my daughter or my wife, what would i do?....
last off, paul and his comrades were traveling the region of phrigia and galatia, and they were actually stopped by the Holy Spirit form going in there and preaching the gospel, then they also tried to enter another town but the Spirit would not allow them to do so.
later that night paul had a vision of a macedonian man standing and beggin him," come over and help us. so right after he had that vision they left for macedonia to preach the gospel there.
so here we see another situation where the Holy Spirit worked in a very convincing fashion, hence people heard the gospel in macedonia.
we see how He enable us to be bold in all aspects, to lose any sense of embarrassment when telling people about Jesus, sometimes we do not find the words or the right timing but He leads us, right before Jesus was crucified when He was promising the disciples the Gift of the counselor He told them that the Holy Spirit would remind them of all the things He had said.
cheers.