I would be inclined to trust a detailed chemical analysis of the raisin, and believe it really grew/aged, and I would distrust the note, which could more easily be faked. Of course, in this scenario, I would be wrong.
Unfortunately, that's all the information and evidence we have on hand and can test. As wrong as it might be in this specific posited scenario, we have no reason to distrust the evidence we observe in the reald world under normal circumstances.
For the rest of us who haven't adopted a preconceived religious based position before looking at the evidence, of course this is the only outcome. It'd be interesting to hear what a Muslim would say, a Jew, Hindu and Bhuddist too for that matter... either it was their Gods or they'll follow the evidence. I can hear AV now saying "they're wrong because, Jesus, etc." but they'll all be saying exactly the same thing about Christianity.
These challenges are a never ending stream of pointless suppositions about scenarios that I'm sure aren't even grounded in his own version of Christianity. I could ask pointless questions too like "Voltron appears out of nowhere one day to wreak havoc all over Japan... What if Richard Dawkins, Daniel Dennett, Sam Harris and Laurence Krauss were chosen to be the Power Rangers, could they beat Voltron?" - it just isn't going to go anywhere worth discussing because it's make believe and the evidence available for it is a big fat "BLANK". My challenge I'm sure makes as much sense to Christians, Muslims, Jews, Hindus and Bhuddists equally as AV's challenge looks to Atheists, Muslims, Jews, Hindus and Bhuddists.
The only thing that should be considered in this reality are observations and evidence that is verifiable to everyone in this one and only reality we share, regardless the world view you want to believe in at home.