They do a good job of proving Biblically that there is a literal, seven year Tribulation, the details of which are described in the Book of Revelation.
I've always said that Christians can have disagreements over the timing of the Rapture as long as no Scripture is denied in the process of coming to a conclusion. The Scripture on the fact of the Tribulation actually occurring, and lasting seven years as given at the site, is correct so I'll just say there is hope for the person who put up the page to "evolve" in their Rapture beliefs :).
I evolved, maybe that is the process? To me I the division between The church and Israel is key and I do not like mixing them together. This is where all the confusion comes in understanding end time events IMHO.