The good:
* Great point about the numbers killed in the inquisition. I didn’t know that, and will definitely use it!
The bad:
* I pulled up The Origin Of Species on Google Books. It doesn’t contain anything that you described. So I crossreferenced with the history of Eugenics. It was Darwin’s half-cousin Francis Galton who came up with it based on Darwin’s research, not Darwin himself. Darwin and he exchanged a number of letters, but Darwin apparently disagreed with his notions.
* Atheists usually like Keynsian economics, and credit the financial collapse to the world straying from Keynesian ideals and toward deregulation. Pointing out that Keynes was an atheist will just earn atheism brownie points to them.
* I don’t think you’ve actually read Nietzche.
Neutral:
* The charity one is good, but I’d do it differently — I’d simply point out that, despite all of the Humanist pontificating that they’re charitable out of their interests in the good of humanity, statistically, religious people give notably more.
You looked at the wrong Darwin book. Check out his "The Descent of Man" (as noted in the article) and them come back and tell us what Darwin thought about eugenics and what to do with the "inferior" types of humans. Scary stuff.