Why are you so sure?
Plus it's not based firmly in scripture, it's an obscure reference that I believe, and many others believe, has been taken out of context with scriptural evidence to show otherwise.
Proponents of the rapture can't even agree at what period of the tribulation that it's going to take place in.
I find it interesting that Christians who believe in the rapture and commit all kinds of sin think that Jesus is just going to take them out of this world when things get tough.