Jesus told his disciples that he will return only once and that when he does, after a time of great tribulation, it will be visible to everyone and be followed by immediate and dire consequences for those unprepared and for those who were adversaries of God.
The disciples expected that Christ would "come" as King, with a royal presence, and to remove the Romans and thrown down the corrupt temple, all at the same time and soon! It was a disappointment for them it turned not out that way, but they came to understand we could have an even much better future because of what Jesus had done. Though they also became convinced of the necessity to be prepared for the time that Jesus would return and that each believer could add by his effort of preaching, to bring the time closer.
All Christians are commissioned and obligated to be evangelizers wherever they are, in that they preach the good news to all sorts of men.
The followers of Jesus were convinced who he was and why his task given to them was so important. They continued bringing without letup teaching and declaring the good news about the Christ, Jesus, and asked their pupils and converted followers to do so too. Coming closer to the end times it is even more important because the world shall not be interested in God and many brought away from the Only One true God, by false preachers and mega churches.
Always there have been real followers of Jesus who only worshipped his One God, the God of Israel. Many centuries they worked and preached behind closed doors, avoiding persecution and death on the balefire. In fear of the stake for centuries the real followers of God baptised people in their faith, not demanding to be part of one or another church but being part of the Body of Christ.
Unmasking anti Jehovah sites and people 