Theophilus means "lover of God." We hope all Christians will be lovers of God. Luke is writing to someone who wants to know about the details of Jesus' life. Luke got them all secondhand -- just as we do -- but Luke had met some who had firsthand knowledge of Jesus, and he is reporting their experiences right up to the day Jesus was taken back up to heaven. They gave convincing proof that Jesus suffered and then rose from the dead and then he appeared to the disciples (students) who had now become apostles (missionaries) because they now had a message to proclaim.