Luke omitted Jesus' warnings about false prophets that Matthew and Mark recorded (Matt. 24:23-28; Mark 13:21-23). Perhaps he did this because he had included similar warnings in his account of Jesus' earlier teachings (17:21-23). Clearly Jesus was now speaking again of events that would precede His return to the earth (v. 27).
21:25-26 Tribulation conditions at the end of the times of the Gentiles are again in view (cf. vv. 10-11; Rev. 6-18). The scope of these crises is global, not just in Judea (cf. vv. 20-21). Probably we should understand the roaring of the sea literally since Jesus also mentioned waves. Evidently the disturbances in the heavens will affect the tides and waves causing great insecurity. Global catastrophes will portend even greater trouble to come for those living on the earth in the Tribulation, and they will fear greatly. The universe will appear to be about to break up.
21:27 When conditions are at their worst people living on the earth then will see the Son of Man coming in a cloud with power and great glory (Dan. 7:13; cf. Luke 9:36; 2 Pet. 1:16-17). He will come to set up the messianic kingdom and to reign on the earth for 1, 000 years (Dan. 7:14; Rev. 20:1-6). The cloud may be the Shekinah (cf. Acts 1:9-11).
21:28 These calamities should have the result that believers living then will realize that the Second Coming is very near. Consequently they should prepare to meet the Lord. The approach of their redemption refers to the approach of the final stage of their redemption, namely their entering the safety of the kingdom (cf. Ps. 111:9; Isa. 63:4; Dan. 4:34). When Jesus returns, He will remove believers from the Tribulation by ending it. This verse contains encouragement for believers. Lifting up the head is symbolic of hope and rejoicing (cf. Judg. 8:28; Job 10:15; Ps. 24:7; 83:3).
