That day means the day when Jesus’s return is imminent, the start of End Times.
Jesus told us that we would see the signs He gave us, similar to when the seasons change. He said we would be able to see the start of end times (which I think we are in). I also believe that Christians will be caught up to meet Jesus in the air.
The Tribulation will be horrible for those left on earth, like these deluded people.
I certainly think we are in the birth pangs of the GREAT TRIBULATION ERA.