Mark wanted to tell his community that Jesus had warned his people that unless they listened to his message about the Kingdom of God they would be punished. Like the prophets Jeremiah and Ezechiel, Jesus is portrayed as an apocalyptic preacher. This means that means that signs and symbolic words are used to describe a climatic event. It means that in the end times serious things will happen. God, of course, will be victorious and rescue those who are faithful.
Apocalypses follow a pattern.
The writer first, tells in the form of future predictions, historical events that have already happened. It foretells cosmic events such as the general resurrection, the last judgment and the end of the world as we know it. Our first reading from Daniel is a good example. It tells a story of the past, during the Exile when a prophet called Daniel remained faithful to God. The author is trying to encourage people of his time, who are suffering persecution, with words of comfort.