Luke 21:36

Praying brings spiritual strength to maintain alertness. It enables disciples to withstand their temptations to depart from God’s will and consequently stand before the Son of Man, when He returns, without shame. Faithful perseverance in the midst of persecution is in view (cf. Luke 21:19).

The people who first heard Jesus give this exhortation needed to trust in Him and commit themselves to remaining true to Him since hard times lay ahead of them. This was especially true of Jesus’ disciples. If the Tribulation had begun shortly after Jesus’ ascension, some of them who became Christians after the Rapture would have been in it and would have anticipated His return in just seven years. After the church began on the day of Pentecost, believers could have been raptured at any moment. After the Rapture, the people who became believers could anticipate the Lord returning at the end of the Tribulation, and they would need to be ready.

Luke’s original readers evidently lived after Pentecost and before the destruction of Jerusalem. [Note: See my introductory comments on the date of composition.] Most of them lived to witness the fulfillment of Jesus’ prediction of Jerusalem’s destruction. This event would have encouraged them to believe His teaching about His return and to prepare for it. They could have met the Lord anytime if the Rapture occurred during their lifetime.

As history has unfolded, we know that the Second Coming is still future. Before that the Tribulation must occur and before that the Rapture. The New Testament apostles voiced many of the same warnings urging watchfulness in view of the Rapture that Jesus gave in view of His second coming (e.g., Romans 13:13; Galatians 5:21; Ephesians 5:18; 1 Thessalonians 5:4-11; 1 Thessalonians 5:17; et al.). After the Rapture, people who become Christians will need to remain vigilant because they will go through intense persecution in the Tribulation. For them the Second Coming will be only a few years away.

Jesus’ exhortation to be watchful is therefore applicable to all disciples regardless of when they may live before His second coming. Vigilance is essential because the Lord’s return is imminent (i.e., impending, overhanging) regardless of when we live.