This document discusses how to become a witness for Christ. It describes Jesus' ascension into heaven and the disciples returning to Jerusalem. The disciples devoted themselves to prayer with Jesus' mother Mary and brothers. Peter addressed the group of 120 and said they must choose a new apostle to replace Judas. Two men, Joseph Barsabbas and Matthias, were chosen. They prayed and cast lots to decide, and Matthias was selected to replace Judas and become one of the twelve apostles. Becoming a witness for Christ requires faithful obedience and trusting what is known to be true.