What part of 'you know not' do you not understand?

Christ comes as a thief, in an hour and a day in which we think not. It is better to live the Christian life in daily expectancy that Christ may return for his church today!

But of that day and hour knoweth no man, no, not the angels of heaven, but my Father only. - Matthew 24:36

Watch therefore: for ye know not what hour your Lord doth come. - Matthew 24:42

But of that day and that hour knoweth no man, no, not the angels which are in heaven, neither the Son, but the Father.- Mark 13:32

And this know, that if the goodman of the house had known what hour the thief would come, he would have watched, and not have suffered his house to be broken through. - Luke 12:39

Remember therefore how thou hast received and heard, and hold fast, and repent. If therefore thou shalt not watch, I will come on thee as a thief, and thou shalt not know what hour I will come upon thee. - Revelation 3:3

Behold, I come as a thief. Blessed is he that watcheth, and keepeth his garments, lest he walk naked, and they see his shame. - Revelation 16:15