For then there will be great tribulation, such as has not been from the beginning of the world until now, no, and never will be. And if those days had not been shortened, no human being would be saved; but for the sake of the elect those days will be shortened. Then if any one says to you, ‘Lo, here is the Christ!’ or ‘There he is!’ do not believe it. For false Christs and false prophets will arise and show great signs and wonders, so as to lead astray, if possible, even the elect. Lo, I have told you beforehand. So, if they say to you, ‘Lo, he is in the wilderness,’ do not go out; if they say, ‘Lo, he is in the inner rooms,’ do not believe it. For as the lightning comes from the east and shines as far as the west, so will be the coming of the Son of man.
Matthew 24: 21-27