This is an excerpt from Forgotten God by Francis Chan:
"A multitude of people had gathered. Peter preached a powerful sermon, and when they heard his words, they were 'cut to the heart' and asked how they should respond. Peter answered, 'Repent and be baptized every one 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, everyone whom the Lord our God calls to himself' (Acts 2:28-39). The text says that on that day around three thousand people became part of God's kingdom and accepted the gift of the Holy Spirit.
"...When I was preaching through this passage at my church, my seven-year-old daughter, Mercy, understood. She came to me afterward and said, 'Dad, I want to repent of my sins and be baptized and receive the gift of the Holy Spirit.' I loved the simplicity and greatness of her faith. She didn't need to debate the finer points of how and when, exactly, the Holy Spirit would come. She just wanted to obey the passage to the best of her ability. I realize Mercy doesn't have the biblical knowledge many of us do, but I wonder how many of us have the faith she has.
"Is that your response to the Word? Is it clear to you that you're supposed to repent, be baptized, and receive the Holy Spirit? If so, have you done it? If not, what keeps you from doing it today?
"Why do we sometimes feel that we need to debate this endlessly, running through every possible hypothetical situation and answering every theological question first? When will we simply respond to the truth we have heard and then work through our questions from there?" (pages 68-69).