Why do you think the author put in the encounter between Calpurnia and Lula?Think about the reasonableness of Lula's position. Wouldn't you ne...

In my opinion, the author is trying to do the following
things when she has Lula reject the white children (and the rest of the congregation
embrace them).

I think that she is trying to show that the
black community is not monolithic -- it has differences of opinion within
it.

I think that she is also trying to show that most of
the black community is tolerant.  This is meant to be a contrast with the white
community where only a few are tolerant and almost everyone else is
not.