Even if Darwin believed that, so what? Newton was also a practising alchemist. It's the evidence that counts, not the personal beliefs of the messenger. Theists of all stripes have never managed to grasp that.
At the age of five, Skagra decided emphatically that God did not exist. This revelation tends to make most people in the universe who have it react in one of two ways - with relief or with despair. Only Skagra responded to it by thinking, 'Wait a second. That means there's a situation vacant.'