After Jesus’ death and resurrection He showed that He was alive with many proofs, appeared to the disciples for 40 days and spoke about the kingdom of God. When the Holy Spirit comes they will receive power, and will be Jesus’ witnesses in Jerusalem, Judea and Samaria, and to the end of the earth. Jesus was lifted up and a cloud took Him out of their sight. Two men who stood in white robes told them that Jesus will come in the same way He went up to heaven. They were together after a Sabbath’s day journey praying, and Peter preached the Bible and made the application that another man should take the office that Judas betrayed. They prayed for God’s help, they cast lots, and Matthias was numbered with the 11 apostles.
Jesus Christ will return, He has not forgotten His people, and the fact that God brought this text to us 2,000 years later on the other side of the world is validation that they were indeed witnesses to the end of the earth.