A more curt, but more direct response would be: As a Christian Nun, you wouldn't even be in Zambia if it weren't for explorers increasing the bounds of our knowledge. Apart from the Copts in Egypt, there's not a lot of 'native' Christianity in Africa.
Given the location she may have been a C of E nun, but if she was Catholic, another curt response would have been: Why doesn't the Catholic Church spend its incredible wealth on the starving children? Why is it immune from the question of 'what's more important than hungry kids'? The Catholic Church is an astoundingly wealthy organisation and could make a mint from sales of both art and property, both of which they have plenty lying unused.
On the other hand exploration and colonization can make place for many more billions of potential Catholics and ensure the sect survival in case of a global extermination event.
