Surprise! A lot of people die on that day. It's not going to be pretty. Just read Malachi and in chapter 2:
2. "But who can endure the day of His coming? And who can stand when He appears? For He is like refiner's fire and like fullers' soap.
3. An He will sit as a smelter and purifier of silver, and He will purify the sons of Levi and refine them like gold and silver, so that they may present to the LORD offerings in righteousness."
5. "Then I will draw near to you for judgment; and I will be a swift witness against the sorcerers and against the adultereres and against those who swear falsely, and against those who oppress the wage earner in his wages, the widow and the orphan, and those who turn aside the alien, and do not fear Me," says the LORD of hosts."
Yowza - read the whole book, its only 4 chapters.