First comes the Rapture where anyone, regardless of denomination or religion, who believes that Jesus died for their sins and allowed him to become their Lord and Savior, is taken up to heaven.
Next comes 7 years of horror called the Tribulation. The first 3 and 1/2 years will be bad, but then the second 3 and 1/2 years will be worse. During that time, the Beast whoever or whatever that is, will make everyone who is still alive take a mark on his/her right hand or forehead to be able to buy or sell. Some form of 666 is to be used.
Back in the 1970's there was a very famous book called the "Late Great Planet Earth" by Hal Lindsey. It spelled out how everything would go down.
Back then, we didn't have the technology we have today that would be able to track people and mark people with the infamous 666. Now we do. Those little microchips they already use to put in the necks of family pets could just as easily be used in people. Bar codes could also be used for easy scanning.
Ok, to continue, during those 7 years of horror there will be 144,000 Jewish (Not Jehovah Witnesses or Mormons or anything else) Jewish evangelists that will go throughout the world telling people there is still time to repent and beome born again before the end of the world. Now, before you think, "Ok, I'll just wait till the Rapture happens and then get right with God," I should warn you, it will be a perilous time. There will be Earthquakes, fires, famines, wholesale murder etc. during those 7 years. You may or may not get that second chance to get right with God.