Romans 10:9-13 That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation. For the scripture saith, Whosoever believeth on him shall not be ashamed. For there is no difference between the Jew and the Greek: for the same Lord over all is rich unto all that call upon him. For whosoever shall call upon the name of the Lord shall be saved.
If a person is saved and the rapture happens as you believe it will, I don't see where the saved person will be able to “choose to stay behind”...even if they don't expect the rapture to happen.
Who said that a person must be correct on his understanding of end time prophecy in order to be saved?