Why are three "Comings" a problem?

I have been reading up on various eschatological views and I have noticed an argument that I have not been able to find a detail about. It seems to be a common assertion by the Catholic and Orthodox that the Rapture, as portrayed by the Left Behind series, is non biblical because it calls for three "comings" of Jesus. [catholic.org](http://www.catholic.com/tracts/the-rapture) puts it eloquently enough, > The problem with all of the positions (except the historic, post-tribulational view, which was accepted by all Christians, including non-premillennialists) is that they split the Second Coming into different events. In the case of the pre-trib view, Christ is thought to have three comings—one when he was born in Bethlehem, one when he returns for the rapture at the tribulation’s beginning, and one at tribulation’s end, when he establishes the millennium. This three-comings view is foreign to Scripture. Does the bible specifically limit the number of times that Jesus comes to earth? Why would it be a problem for Jesus to come again before the "Second Coming"? Where does this "only two comings" requirement come from?