(Reminds me...)
I want to add that both Jehovah's Witnesses and the Latter Day Saints (which both believe their interpretation of the bible is the only true interpretation) practice two forms of argument that is not readily seen in other religions.
The first is provenience of divine literature. The LDS believe that the Book of Momon (etc.) was granted through direct communication with god. Subsequent literature is as well. Jehovah's Witnesses believe the same regarding each of their publications from the start of their movement. The “Life – How did it Get Here, By Evolution or Creation” book uses decades-old science references and an inclosed mentality that is so easily proven wrong, it's almost laughable that it's still in print. Yet they (like the LDS) think that this book is divinely granted to them to read, study, and share... BY GOD.
No other religion readily does this. The most popular publications in all of fundamentalism history, the Chick Tract series, is not written by direct communication with god, but is inspired by a literalism view of the bible. In fact, in may works of literature that is granted approval by use in religion is the result of the word of god inspiring such writing, not god himself.
The second thing they both do is use the “at least we're not THEM” argument as a method of proving that they are the right path to salvation. Now, many fundamentalist groups readily point out the faults of other paths, but they shy away of condemning other religions as a general acceptable form of persuasion... mainly because it's a lame argument that doesn't actually prove anything. The Catholic church does not say “look at all the harm the Baptists do regarding _____” as a means of skirting around child abuse scandals, for example. The finger-pointing, fault-finding, and tearing down of other people's faiths as a method of “proving” their own validity is something done on a personal level and sometimes a perish level, but NOT as a general practice from church leaders. And both these religions practice this method of “clouding” and “deflection” when it comes to bible study universally.
So with all this, you would be hard pressed to convince me that whether a person's salvation is on heaven or on earth is of any real importance to the discussion.
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A word about the first century Christians. There were several forms of Christianity, all squabbling among themselves... very much in theme with latter part of this thread... LOL.
The Gospel of John and the three letters clearly form one version of Christianity of the separatist church. Mark, and later Matthew dealt with a different form of Christianity, one that sought to reconcile their heritage and their beliefs – Jesus didn't replace the Law, he improved upon it. Jews could follow the Law as a means of personal culture (Gentiles did not) but follow Jesus as a means of spiritual enlightenment. Thomas took another (closer to Gnostic) form of Christianity east to India and Asia. The Gnostic faith was spreading in the south of the Levant region as well. There was a Christian faith spreading among the Jews in Egypt (not too much is known about them) and the Ethiopian eunuch of Acts 8:26-40 would have taken another form of Christianity to Ethiopia and other parts of Africa. Similar with Babylon. And Paul had his form of Christianity that became present in Rome.
So when you talk about the first century Christians, you have to understand that they were no better off than we are right now... tons of different factions all believing different shades of the same story. It took a political power (Constantine) NOT a godly power to formulate the Christianity we know today including the bible canon the JWs and LDS swear by.