Darwinism saith Dawkins, is the philosopher's stone that allowed Dawkins to be an intellectually fulfilled atheist. That is like an Arabian saying that Mohammed's Koran is what what allows him to be an intellectually fulfilled muslim. Or even perhaps like we Jews saying that the Torah of Moses it what allows us to be intellectually fulfilled Jews.
Do you call Mohammedism a religion? Do you call Judaism a religion? Do you call atheism a religion?
To teach Darwinism, without bold warning and disclaimer, is religion, as Dawkin's words tell -- it is the teaching of atheism.