Moral argument
Not exactly. Russell knifes metaphysics to say there is no god. Copleston says that without metaphysics there is no morality. Therefore, he tries to demonstrate the futility of having moral discussions [absolute right, absolute wrong, absolute good, absolute evil] without metaphysics.
ie if this involves a contradiction, there is a flaw in the argument, similar to the contradiction in classical set theory paradox.
ie if you cannot touch right and wrong, then what is it if not metaphysical?