The Tribulation Force is a fictional Christian-based group composed of those left behind after the Rapture, as portrayed in the fiction series Left Behind by Tim LaHaye and Jerry B. Jenkins.
In a series of events that followed the Rapture, in which Jesus Christ takes away members of his church from Earth, Rayford Steele, Chloe Steele, Buck Williams and Bruce Barnes find themselves left behind. Eventually they meet at New Hope Village Church, located in the suburbs of Chicago. They then meet from time to time and become immersed in study of prophecies contained in the Bible. Their study reveals that the Antichrist will establish control of the Earth, and the Tribulation period lasting seven years will start after his covenant with Israel. Jesus Christ's second coming will fall on the end of the Tribulation.
In the course of their study, they form a core group Chloe Steele christens the "Tribulation Force", dedicated to opposing the Antichrist. This group of believers, as well as others left behind but becoming believers, are otherwise known as "Tribulation Saints", to differentiate from the pre-Rapture designation of Christian. Over time, some members of the Trib Force become martyrs for their faith and others come to join. In the end, only one of the original four Trib Force members lives through all seven years of the Tribulation and witnesses the Glorious Appearing of Christ, although the others are resurrected afterwards.