Jesus replied that as the Son Of Man He didn't know the day when the end would take place, because that was known only to the Father. But He told them many things that would happen in the end days by which they could know that the end was near. (The destruction of the Temple took place during the lifetime of many of the disciples.)

Jesus said that in the end days, the people of the world would turn against His disciples and hate them. Many would be taken to court and put to death, and many would be betrayed by their own family members. There would be many wars and rumours of wars on earth, sicknesses, earthquakes, famines, floods, etc., in an increasing manner. There would arise many false teachers, prophets and miracle workers using the name of Christ but actually turning people away from God, proclaiming false teachings about Christ, some even claiming they were Christ, bringing false anointing and doing false miracles empowered by demons in order to try and deceive even true children of God. Because of the pressure to give in to sin coming upon them, some who stood faithfully till then would give up. Many would get deceived by the miracles that would take place and false teachings based on misplaced quotations from God's word.

Jesus tells us not to allow ourselves to be fooled by all such deceptions but to be alert to identify them and to keep ourselves faithful to Him. We are not to fall a prey to impressive proclamations from people, even if they carry out supernatural works we cannot explain. We are not to be fooled merely because they use God's word or use the name of Jesus as their authority. He tells us to identify false workers by looking at their fruit--whether they show the fruit of the Holy Spirit in their personal lives and also in the lives of those who follow them.

In the end, suddenly Jesus would appear in the sky announced by the trumpets of angels, and all His true disciples would be gathered from all over the world to be with Him.