I do see your point, WW, but I think if you look at the entire quote

"A doctor examining one of his more crapulent patients said to him,
'Your body is a temple and your congregation is too large.'"

the idea of size enters into it. If crapulent means suffering from excessive eating or drinking, I find the use of the comparative "more" somewhat strange. And if you substitue "sicker" for more crapulent, the second part (large congregation) doesn't really fit. In the totality of the statement, at least the way I'm reading it, corpulent still would have been the better choice.