Calculating the date of the return of Christ may be theologically intriguing, but it is practically irrelevant.  If Jesus Himself chose not to know and said that nobody else knows (Matthew 24:36), why has there been a succession of 'end of the world' frenzies?  The greatest religious delusion (apart from assuming to be God) is the desire to be in control of the future.  It is not only occultists who specialise in prediction; religionists of all flavours do this as well.  Interestingly all such 'prophetic revelations' have proved false although lots of people's lives have been cultishly controlled in the process.

Watching for Christ’s return is not intended to be a predictive exercise, or even an intensive comparison of Bible verses to arrive at a date.  It is simple - it is the confident expectation that He will return and that the event could happen today!  With that deep heart-longing and expectation is an inner desire to please the Lord by obeying what He says (1 Thessalonians 1:9-10).  The 'watching' is therefore to be accompanied by getting on with the daily business of serving the interests of the Master's business (Luke 19:13).  

The Lord’s work is not just done in a church context: it is a lifestyle of serving the King of kings in the home, community and workplace.  It is a daily practice of walking in step with the Spirit (Galatians 5:25) until we see Him face to face (1 Corinthians 13:12).  A good test of our state of readiness is to ask, ‘If I knew that Jesus will come back tomorrow, what will I do today?’  If the answer is anything different than you have already decided to do, you are neither ready, nor watching!  Jesus' words are accompanied by a warning, “… do not let Him find you sleeping”.  Matthew 25:1-13 says that those who are not awake to their spiritual responsibilities are excluded.  The disciples were to have a dramatic test of their ability to obey.  In the Garden of Gethsemane Jesus calls the trainee apostles to stay awake, watch and pray; but they failed the examination (Mark 14:32-41).  It was a lesson Peter never forgot because he wrote in 1 Peter 4:7, “The end of all things is near. Therefore be alert and of sober mind so that you may pray.”

The times when we are least awake are the times of greatest vulnerability.  Sleeping on the job is not good business practice.  Yet many believers go for weeks or even months without any thought that Christ may come today - and live as though He will not!  With their horizon set on earthly things, they please themselves, live in survival mode, practice a weekly religion, have no care for the lost souls around them and no personal confidence in times of trouble.  Colossians 3:2-4 says, “Set your minds on things above, not on earthly things. For you died, and your life is now hidden with Christ in God. When Christ, who is your life, appears, then you also will appear with him in glory.”  So, Jesus' words to everyone, "Watch!" applies to us as well.