After the first half of 7 years of trials and tribulations, the antichrist will break the peace treaty with Israel. He will then go into the temple of God and declares himself as God (2 Thess 2).
There will be an image made of him that will be animated - this image will actually speak too. He is going to demand people to worship him to be able to buy and sell. This is where the mark of the beast comes in - it's a simple policy: "Worship me or starve".
Dr. Mark Hitchcock stresses that we can't really fathom what that time period will be like in the future. That's why the most important thing for us is to be ready and make sure that we won't be here for that time of trial and tribulation.