“And it shall come to pass afterward, that I will pour out my Spirit on all flesh; your sons and your daughters shall prophesy, your old men shall dream dreams, and your young men shall see visions. Even on the male and female servants in those days I will pour out my Spirit.”
And I will show wonders in the heavens and on the earth, blood and fire and columns of smoke. The sun shall be turned to darkness, and the moon to blood, before the great and awesome day of the LORD comes. And it shall come to pass that everyone who calls on the name of the LORD shall be saved. For in Mount Zion and in Jerusalem there shall be those who escape, as the LORD has said, and among the survivors shall be those whom the LORD calls.”
The apostle Peter quotes this passage in his sermon at Pentecost right after the believers recieve the gift of the Holy Spirit. This is a gift that God has given not only the early church, but all those who have trusted Christ as their Lord and Savior. We shouldn’t get hung up on the spiritual gift/sign gift debate, but rather give thanks to God that He gave us a Helper to open our eyes to His truth, to empower us for His work, as a sign of our salvation and to cleanse us (and that is just some of what the Holy Spirit does for those in whom He dwells). Cool.