The Rapture and the Great Tribulation
The Bible teaches:
1. IF a person believes in Jesus Christ, repents, is baptized, receives the Holy Spirit, has a personal relationship with Jesus Christ, and dies, they will go to heaven regardless of their belief (or lack thereof) in WMB's teachings. That is, they are saved by grace through faith in Jesus Christ ALONE.
The Message teaches:
2. IF a person believes in Jesus Christ, repents, is baptized, receives the Holy Spirit, has a personal relationship with Jesus Christ, and is alive at the RAPTURE and does not believe the doctrine/teachings of WMB, they will go through the tribulation. They must give their life for the Gospel to be saved. They are saved by grace through faith in Jesus Christ PLUS they MUST GIVE THEIR LIFE for the Gospel.
That means, according to Message teachings, in order to go in the rapture, faith in Jesus Christ is not sufficient, they also need to follow WMB. So if a a non-message believer (but sincere Christian) is unfortunate enough to be alive at the rapture, they are not saved unless they give their life for the Gospel.