The context is the same as the above parable. Jesus has just told them about the tribulation and the second coming.
What should the response be to seeing the signs? “How can one avoid being caught off guard at the return of Christ?
The time of the return is unknown, so be alert, watch and do not be caught sleeping. It is helpful to understand the cultural background here because anyone caught sleeping on guard was executed.
Watchfulness = belief or faith.
The Olivet Discourse primarily concerned the return of the Lord at the Second Advent. Those who will be alive and to whom the signs of the heavens will appear are urged not to get caught off guard by the sudden return of the Son of Man.
The Biblical context demands a time frame at the end of the tribulation and not before the rapture for the interpretation of this parable, although the application may extend to those in the church expecting the rapture. If the second advent of Christ to the earth is imminent, how much more the rapture?
Faith in the soon return of the Lord will be demonstrated by watchfulness and alertness.
Knowing the judgment that awaits the unbeliever, I should be sure I am saved and seek to warn others so they can be saved.