Pretribulational eschatology teaches that the rapture is “signless” or “unannounced,” while the second coming will be preceded by signs and thus “announced.” There cannot be any intervening prophetic events or signs that will occur before the rapture. Hence, it can happen at any moment. If just a single, biblical, prophesied event happens before the rapture, then Christ’s return can no longer be considered imminent.
This is why I have always found it ironic—and contradictory—that it is pretribulationists who seem to be fixated about this or that prophetic sign happening right now. Many of the popular sensational pretrib teachers cannot resist talking about “signs” happening at the present time, not realizing it is inconsistent with their imminence theology. This is the case for Calvary Chapel pretrib pastors and teachers as well as a host of other pretrib teachers from other denominational circles.