In what way is the Resurrection the best explanation?

[GrandizerII]

That's Jewish apocalyptic prophecy for you. It's a jigsaw puzzle you do after the events have given you the picture to work towards.

But purportedly important Messianic events (such as the Resurrection) aren't contained anywhere in the OT. Doesn't this serve as some evidence against what you're saying?

Again, the non-Christian Jews (from what I've read) don't accept that Isaiah 53 is about a person, let alone a Messiah.

Check out Wikipedia for counterexamples, but I must stress Isaiah 53 applies to both a nation and a person acting on behalf of the nation.

The standard non-Christian Jewish interpretation is still that Isaiah 53 is about a nation and never a person. There are three other such passages pointing to the Servant as a nation, if you look at these passages within their context.

I get as a Christian you interpret it as applying to a person, but the problem here is that Isaiah 53 doesn't specifically point to Jesus and the specific events around him even if it was about a particular person.

Incredibly biased sources, and scant/undocumented relevant details in contemporary "neutral" records, means we can't really convincingly speculate what exactly happened.

Vicki, come on, you're intelligent enough to know what's wrong with this statement.

Yes, nothing is wrong with the statement.
If you want to know what the Liberal Democrats believe, you read their manifesto. Sure it's very biased towards the LDs, but it tells you very accurately what they believe.
If you want to know what C1 Jews believed, read Josephus. Sure it's very biased towards C1 Jews, but it tells you very accurately what they believed.
If you want to know what the Early Xians believed, read the NT. Sure it's very biased towards Early Xianity, but it tells you very accurately what they believed.

Ok, I get the part in italics, but nevertheless the fact that they are biased sources means they are going to give you their preferred interpretations in light of these biases. C1 Christians writings weren't meant to be taken as objective sources of history, rather they were meant to be documents promoting particular theological beliefs with some backstories to them.

Could you unpack the Bart Ehrman explanation a little, please?

Don't worry about him. I've only read a couple books by him, and in those books he doesn't address the Resurrection head on. And when he does, from what I've read in articles by him, he doesn't go as far as I do with my OP (I'm actually being rather generous to Christians with my OP). My point in bringing him up is that he does provide a clear context in which the Resurrection belief could have come up, but since this is more fully tackled in Tim O'Neill's post, let's focus on that instead.

However the much repeated problem still hasn't been resolved. 
He doesn't explain why the disciples kept the whole thing going, let alone proclaimed that Everything Has Changed.
He doesn't get us from the dead wannabe Messiah waste man to the Pauline embodiment of God who has inaugurated the KoG.
He doesn't explain why the Earliest Church concluded that death had been defeated. Seeing a vision of someone who's died is a pretty conclusive indication that they're still very dead. But the disciples were clear on this- Jesus was alive!

The belief kept going because they sincerely believed it and they were successful enough to keep it going.

I'm not sure what's remarkable about the inauguration of the KoG when there's no evidence this has happened, just Christians believing the KoG has been inaugurated.

Early Christians concluded that death had been defeated because they had concluded that Jesus must have risen. Tim addresses how this could have been possible by appealing to common human psychology. He does so near the end of the article.

We don't know. That's the point I'm trying to get people to understand.
At the same time, we can still offer potential accounts of what might have happened, in spite of the lack of evidence and relevant details,

But none of the accounts put forward are plausible. Given centuries of high powered scholarship has failed to come up with a sensible alternative, perhaps the time has come to say the disciples actually knew what they were talking about?

I really don't see how many of these accounts put forward aren't plausible, but I get how it wouldn't be in your best interests to agree with me on this.