If you read St. Alphonsus and if you reference the biblical commentaries of Fr. Haydock, St. Thomas, and Cornelius a Lapide, you'll find that the verse in which one worker is taken and the other left behind refers to the mystery of predestination - that is, wherein among a group of seemingly similar people, certain souls are more favored by God through His mysterious designs. Ultimately, resulting in the salvation of one and the loss of grace in the other, though they both seem the same.
It is unbiblical because it has no links to the teachings of the Apostles. The modern notion of a "Rapture" was invented in the 19th century. If you look up the word "rapture" in Samuel Johnson's dictionary there is no mention of this supposed future event.
Aside from that, it makes absolutely no sense.