They go through to another room of the house, where Myshkin is horrified by a copy of Holbein's painting, "Christ's Body in the Tomb." Rogozhin volunteers that the painting has made him lose his faith in God.
(Okay, so a little Shmoop aside to clue you in. This is a real painting that Dostoevsky saw during his travels and that totally made him crazy. Actually, the thing Myshkin says about the painting—that it could cause a man to lose his faith—is actually what Dostoevsky himself said about it when he saw it for the first time. So what is in this faith-shattering painting? It's basically a larger than life, long horizontal painting of Jesus's dead body inside a wooden coffin.)
Myshkin is all, that doesn't mean anything, and throws out a couple of parables about it. In one, an atheist is also a really learned, impressive dude. In another, a peasant asks for God's forgiveness even as he is in the process of stabbing his friend to death.
Rogozhin busts out laughing at this story, which…um, inappropriate much?
Then Myshkin tells his super mentally stable friend about a cheap tin cross he recently bought. Rogozhin proposes swapping crosses, which is a pretty symbolic gesture. Basically, it's like the spiritual version of doing the blood-brothers thing. Myshkin is totally psyched to be Rogozhin's brother, but then realizes that Rogozhin is still all spite and malice towards him.
The new brothers head off through more rooms, and Rogozhin takes Myshkin to see his totally senile mom. She blesses Myshkin.
Finally, Myshkin is ready to go, and goes to hug Rogozhin, but Rogozhin won't have any of of it. Rogozhin suddenly says that he is giving up Nastasya, telling Myshkin to take her.