What the Bible Says
John 7.37–39

On the last and most important day of the festival, Jesus stood up and cried out, “If anyone is thirsty, let him come to me and drink. The one who believes in me, as the Scripture has said, will have streams of living water flow from deep within him.” He said this about the Spirit. Those who believed in Jesus were going to receive the Spirit, for the Spirit had not yet been given because Jesus had not yet been glorified.

Romans 10.8–13

This is the message of faith that we proclaim: If you confess with your mouth, “Jesus is Lord,” and believe in your heart that God raised him from the dead, you will be saved. One believes with the heart, resulting in righteousness, and one confesses with the mouth, resulting in salvation. For the Scripture says, Everyone who believes on him will not be put to shame, since there is no distinction between Jew and Greek, because the same Lord of all richly blesses all who call on him. For everyone who calls on the name of the Lord will be saved. 

Acts 2.32–41

“God has raised this Jesus; we are all witnesses of this. Therefore, since he has been exalted to the right hand of God and has received from the Father the promised Holy Spirit, he has poured out what you both see and hear.  For it was not David who ascended into the heavens, but he himself says: The Lord declared to my Lord, ‘Sit at my right hand  until I make your enemies your footstool.’ “Therefore let all the house of Israel know with certainty that God has made this Jesus, whom you crucified, both Lord and Messiah.”

When they heard this, they were pierced to the heart and said to Peter and the rest of the apostles, “Brothers, what should we do?”

Peter replied, “Repent and be baptized, each of you, in the name of Jesus Christ for the forgiveness of your sins, and you will receive the gift of the Holy Spirit. For the promise is for you and for your children, and for all who are far off, as many as the Lord our God will call.” With many other words he testified and strongly urged them, saying, “Be saved from this corrupt generation!” So those who accepted his message were baptized, and that day about three thousand people were added to them.