Well, that reasoning can apply to anyone who claims to be a part of the body of Christ.
I was just meaning i think being in the 'truth' didn't relate to whether one believes those who died at Sodom and Gomorrah will be resurrected on not or whether one has an organ transplant or not or even to a degree to dates that have been mentioned for armageddon but it relates to the 'good news' the 'gospel' evangelion.
I think it came to mean to me whether one was a Jehovah's Witness or one wasn't but it still related to the witness one was giving whether it was door to door or in one's personal life and the way they were conducting it.
I understand there is a connection to the Roman emperors and their messages. They were considered saving messages, world changing for the better and the power of the 'gospel' is and it comes from God.
In my view one would only be in the 'truth' if the gospel is the same as preached by Paul and the apostles. If that is the same then i think one is part of the body of Christ.
In Ray Franz book In Search Of Christian Freedom on page 539 under the subheading 'The foundation and Essence of the Good News' he writes,
'What did the apostles and other Christian writers emphasize in describing that Messianic rulership and its effects? They consistently pointed to Christ's ransom sacrifice, his victory over kings sin and death on behalf of all mankind, the authority the Father has given to his resurrected Son to liberate from the wages of sin and death all those who put faith in him. That was-and is- the good news the Bible itself brings us. The Biblical good new does not draw attention to, nor is it tied up with, some date, whether 1914 or any other date, nor does it attract by offers of alluring physical and material benefits "just around the corner." It is tied up with and event, the event in which God's Son fulfilled his primary mission as the Messiah and gave his life on our behalf, thereafter being resurrected to God's right hand and serving as our advocate there. Only for this reason could Paul say to the Corinthians, "I decided not to know anything among you except Jesus Christ and him impaled."'