A belief that biodiversity can be explained conclusively and definitively without God.
Now, that's not the same as saying aspects of biodiversity can be explained without resorting to divine intervention.
And it's not the same as saying conditionally that all biodiversity can be explained through natural causes.
It's dogmatically holding the position that all life developed without intervention from God and, no, we don't have to spell out exactly how this happened, and if you question this you are anti-science.
That's what Darwinism is. It's a social movement not a scientific exercise. See the link to Wiki in which the coiner of the word called it "a veritable Whitworth gun in the armoury of liberalism" promoting scientific naturalism over theology . . .
Yes, it is. Prove otherwise.