When the Holy Spirit arrived in a small room in Jerusalem around 2,000 years ago, people weren't quite sure what to make of it. Some said the disciples were drunk when they came out of the room speaking in all sorts of tongues or languages. They weren't drunk, and at the end of the day many people came to faith. The Holy Spirit is a vital part of Christian life, but how does He work? What should we look for? Is He scary?