Great Tribulation

Mat 24:21 For then shall be great tribulation, such as was not since the beginning of the world to this time, no, nor ever shall be. Mat 24:22 And except those days should be shortened, there should no flesh be saved: but for the elect's sake those days shall be shortened. Mat 24:23 Then if any man shall say unto you, Lo, here is Christ, or there; believe it not. Mat 24:24 For there shall arise false Christs, and false prophets, and shall shew great signs and wonders; insomuch that, if it were possible, they shall deceive the very elect. Mat 24:25 Behold, I have told you before.