Just to stick my oar in:
YeaH, didn't virtually all of the early Christians, excepting maybe the Marconites, agree on the importance of Apostolic Succession?
To some extent. All the ones who were what was subsequently labelled orthodox did. But not only the Marcionites but (say) the gnostics would have rejected it too; indeed most of the gnostic texts that we have are effectively attempts to undermine the principle, since they all assert that the teachings of the mainstream disciples were shallow and the "true" teachings were transmitted secretly by some especially privileged disciple (although they can't agree which one).
In fact the notion of apostolic succession arose really as a means of distinguishing between the correct teaching and the incorrect; it was a doctrinal standard. And quite a reasonable one too. But it's big leap from the notion of apostolic succession to the papacy, let alone the notion that the Pope wields the authority of St Peter. It wasn't until the fourth century - hundreds of years after the emergence of the notion of apostolic authority - that any bishop of Rome thought of arguing along those lines.
He was historically the bishop of Rome, which is the pope and his succession is well archived.
No. First, the succession is not well archived at all. As MagisterCultuum correctly says, even the supposition that there was "a bishop" in Rome (or anywhere else) in Peter's lifetime is highly dubious. The fact that Noetus was examined by "the deacons" in Rome at the end of the second century strongly suggests that that church had not yet evolved the monarchical episcopate even by that late stage, so to suppose that it existed in Peter's time or even soon after seems very unlikely.
Even if Peter had been the single leader of the church in Rome, and even if there had been a clear succession of uncontested leaders of this kind, that wouldn't make him "the Pope" unless you take "Pope" to mean nothing more than "the leader of the Christians in Rome". But that doesn't imply anything special.
That is not to say that the Pope doesn't have some kind of special authority, or that he isn't in some important sense the successor of Peter or shares his authority. But these claims are quite distinct from the notion of apostolic succession.
If my religion isn't legitimate, and yours is an offshoot of it, then that makes yours illegitimate too.
Why? That assumes that "legitimacy" of religion is inherited, like some kind of genetic condition. Why should that be the case? And what is "legitimacy" anyway? Surely what matters is whether a religion is
true. And I don't see why a true religion couldn't emerge from a false one, or one that is partially false.
I believe Plotinus said that there is very little evidence that Peter was particularly involved in the church at Rome, and that the church was definitely well established there long before he even visited the city.
Furthermore, there was no office of "the bishop of Rome" at the time. The earliest churches were originally led by councils of elders, with horizontal specializations rather than a vertical hierarchy. Rome was one of the slowest to move to ecclesiastical monarchy.
The closest that the very early church had to a single leader was not Peter but James the Just, the brother of Jesus. (Plotinus also claims that the Catholic church is being very unreasonable when they choose to interpret adelphos to mean cousin or relative rather than brother. The Eastern Orthodox position of claiming that his brothers were older sons of Joseph from a previous marriage seems a little more reasonable, although etymologically adelphos means from the same womb and would seem to fit best with the notion that Mary has other children after Jesus rather than maintaining perpetual virginity)
That's right. Of course,
adelphos could mean "cousin" or something like that; the point is merely that there's no reason at all to suppose that it does, other than the dogmatic (as opposed to historical) belief that Jesus
couldn't have had (full) siblings. But that isn't enormously relevant to Mormonism.
I have a question about the Mormon conception of God. Perhaps this has already been asked. But if God is physical, then where is he? As I see it, there are only three possibilities for something like this: he might be in a particular location in our universe; he might be omnipresent throughout our universe, located in every place; or he might be in an entirely different spacetime altogether. All three of these seem to me to be problematic, for various reasons.
