A simple challenge for atheists

[Esquilax]

Okay, from the abstract to the specific. Just say there was better eyewitness evidence, and Jesus, who claimed to be God, was crucified and rose from the dead (predicting both beforehand). We could observe that:

1. Being dead after a crucifixion was a well know and predictable state
2. The extraordinary evidence required is not only Jesus healthy after a crucifixion, but for 40 days he appeared to many.
3. It is reasonable to assume the cause was the that which he claimed it to be: God.
4. There was a key theological component to the teachings of Jesus that only make sense in light of his death. For one example out of hundred, John the Baptist introduced him as the "Lamb of God who takes away the sins of the world".

I'm fine with this up until point three, because claims of causation are not evidence of causation, even if the effect is supernatural. But then, you still also have little but a hypothetical here; as it stands, the evidence for all this isn't at a level where one could reasonably conclude anything positive about the claims.

So again, if there was better evidence for this event and it was otherwise as the gospel writers described, it would not be illogical to assume:

A. There is no hidden scientific reason to explain this event.
B. There exists extraordinary evidence of the event
C. God was the likely cause of the supernatural event
D. The event was not to make a general point, but rather had a complex purpose.

Are these reasonable conclusions drawn from this set of facts? Would it be correct to say that the rationality of Christianity increases the more reliable the gospels are proven to be.

Again, this is a thought experiment, not a gospel trashing exercise.

Here's the thing: we have to take each claim on its own merit, within the context that it inhabits. The gospels are not one claim, in actuality they're a collection of many claims, some more inherently believable than others, with their own attendant levels of evidence. Demonstrating the truth of any number of claims within should not give us greater confidence in the truth of the others; after all, one hundred true claims do not make a false claim in the same collection any more true.

The most important thing here, with regards to the gospels, is that we differentiate between the mundane claims and the supernatural ones, as they require different levels of evidence to demonstrate reliability, in accordance with how they fit into what we already know about the world. Often, theists will try to prove the reality of the supernatural claims, by appealing to the truth of some mundane ones ("This city depicted in the bible is real! X biblical figure was referenced elsewhere!") but all they're really done is provide a bad argument on two fronts; the one mentioned above, and also the idea that the mere existence of a city demonstrates that magic was performed within it.