Most People Insist That Two Separate Being Can Never Be One

[Vicki Q]

But - as with hallucinogens - one can be perfectly sincere and still be wrong. A Hindu or a Muslim is just as sincere in their beliefs as you are. You can’t all be right.

If John Hick was onto something with his elephant, we could all kind of be right.
Certainly it wouldn't work for me to rule out God doing things through other religions just as He does through Xianity.
I'm not sure how much “Cross and the Switchblade” type things go on in, say Hinduism, though.
If one experienced something requiring explanation, if taking hallucinogens was the obvious explanation, that would be the go to. Whereas if other explanations were weak, it might make very good sense to believe it was God.

No...(confirmation bias)  

They're pretty powerful witnesses because I trust them. Even granting confirmation bias (which is a double edged sword BTW), their experiences would still be evidence, and if the evidence was tight enough on investigation, potentially very strong evidence indeed.

Yes, Lourdes is very strict...only ‘verified’ 70 miracles.  

Gold standard levels of proof.
A wish to use clear exemplars rather than many 'shades of grey' exemplars, of which many exist.
God not doing a slot machine approach to healing.

In any case, Lourdes was an example of the contemporary experience genre. There are so many more...it's a cumulative thing.

Of COURSE...answers your last paragraph.  

First century Jewish messianic movements absolutely did not survive the death of their Messiah. They couldn't in theory because the theology would be completely contradictory, and we know from what first century historians tell us they didn't in practice.

The disciples avoided C1 Israel politics- Early Christianity specifically and repeatedly denied that sort of thing had a role. 

Fisherman were more like middle class in those days.
I don't see, though, how class in any way explains why the disciples thought the death of their Messiah amounts to a declaration that the Kingdom of God has arrived, the sins of God's people were forgiven, and that God had returned to Jerusalem.