New Defender's Study Bible Notes
21:34 come upon you unawares. These verses (Luke 21:34-36) appear only in Luke. The emphasis on the suddenness of the coming of “that day” can only apply to the initial phase of Christ’s second coming, or “the rapture.” Compare I John 2:28.
21:35 the whole earth. The suddenness of the event will take place on the whole earth simultaneously, as Christ had already told them (Luke 17:34-36).