Jesus told his disciples that before he would return in glory there would be earthquakes, famines, floods, wars, plagues and persecution (Luke 21). In fact these things have been going on for so long that even many Christians no longer believe that Jesus will return to the earth just as he promised he would. What seems like a long time to us however, is in reality a very short time.
Monotheism as we know it began with Abraham some 4,000 years ago. From Abraham to David and the establishment of the kingdom of Israel was one thousand years. From David to Jesus was another thousand years. In about 17 years we will celebrate 2,000 years since the death and resurrection of Jesus and the birth of the Church. So while it is true that God is not bound by any number or specific period of time on earth, it is also true that patterns of harmony and symmetry are both aspects of the very Being of God and of the way in which He reveals himself to us.
Modern forms of communication have made it possible for the Gospel to be preached to the whole world. Hence the task that Jesus gave to his disciples has been fulfilled and the present age of the Church is very close to completion as well. So while is true that no one knows the day or the hour when Jesus shall return, I think that the age of the Church will not extend beyond the end of this century.
In the meantime we should recognize that this is a time of preparation. Those who are not in a right relationship with God will be terrified by the events that will happen at the close of the present age. Only those who trust in Jesus and have taken up their cross and followed him will be able to lift up their heads and rejoice at the coming of the Lord.