As theists, we argue that this reasonable and orderly basis behind the universe is none other than the reasoning and personal one who created all, and is himself the ground of all being. When we act as though we are free choosing beings, rather than determined ones, we imply that we believe there is a basis for freedom. Again, belief in personal freedom is only consistent with theism, never with naturalism. As theists, we argue that this basis is the eternally free and sovereignty choosing creator God who has made us in his image. The same goes for morality.
Morality is impossible without free choice.
Suppose I use a chain saw to sever someone's head from his body. When the police come, they arrest me, not the chain saw, even though the chain saw actually did the cutting. The answer is obvious. The chain saw is a machine, incapable of choice. It does whatever I make it do.