Teach them to obey. Matthew was written to record and communicate many of the things Jesus taught in order to help fulfill Jesus' command to make disciples of all nations through teaching them what Jesus' taught. See WLC 108; WSC 50; BC 19, 27, 29, 33; HC 47.
Matthew 28:20
I am with you always, even to the end of the age. Jesus was called Immanuel — "God with us" at the beginning (Matt. 1:23) and this truth is emphasized again. Jesus' disciples live awaiting the time when God is going to bring his kingdom from heaven to earth (Matt. 6:10; 24:1–25:46), which is called the end of the age.