Evolutionary explanation of morality self-refuting?

[Tea Earl Grey Hot]

Hello, first time posting here. I'm coming very close to switching over to atheism. I grew up as a fundamentalist, and defended my beliefs based on the arguments of the usual group of Christian Apologists such as Craig and the rest. But in the past year, more and more about my worldview was making less and less sense. I think what ultimately drove me to seriously consider atheism (or some form of non theism at least) was the work in new testament history and composition by people such as Robert M. Price (which ironically I was made aware of by their loudest opponents such as Habermas).

But anyway, one of the things that is keeping me from leaving theism or at least Christianity is an issue of morality. A typical notion I read is that morality is simply tendencies in humans caused by evolutionary processes. But W.L. Craig (and probably others) say this is self-refuting:

Given the truth of naturalism, all our beliefs, not just our moral beliefs, are the result of evolution and social conditioning. Thus, the evolutionary account leads to skepticism about knowledge in general. But this is self-defeating because then we should be skeptical of the evolutionary account itself, since it, too, is the product of evolution and social conditioning! The objection therefore undermines itself (On Guard, 2010, p. 144).

I'm sure this argument has been dealt with elsewhere but I haven't been able to find any refutations as of yet.