In his massive defense of orthodox theology, Against Heresies, Irenaeus describes the departure of the Church. Pre-tribulation theologians emphasize his specific chronological order: the Church is caught up, and then the global tribulation described by Jesus in Matthew 24 begins.

“And therefore, when in the end the Church shall be suddenly caught up from this, it is said, ‘There shall be tribulation such as has not been since the beginning, neither shall be.'” (Against Heresies, Book 5, Chapter 29, Section 2) Irenaeus of Lyons