What's in a name?

A few other people have posted on the whole "Nature vs. Nurture" debate that goes on throughout Good Omens. Basically, the argument centers around the question of whether or not Adam will end up being the Antichrist who brings about Armageddon just because he is the offspring of Satan. After the babies get switched, it turns out that Adam grows up to be a fairly normal eleven-year-old who would much rather go play with his friends and his dog than go perform an act of evil. Likewise, Aziraphale and Crowley often wonder to themselves if, being angel and demon, they can only end up doing good and evil, respectively. We end up seeing that both of them are able to make choices which are sometimes independent of what one might believe to be the stereotypical angelic or demonic thing to do.
However, in the posts I've seen on all the blogs, nobody has yet addressed a third instance of this debate: Dog. On his eleventh birthday, the child who is the Antichrist is sent a hell-hound as a companion in doing evil and bringing about the end of the world. Because of the fact that Adam knows nothing about his true origins, we obviously know how that puts a wrench in the plan. The hell-hound is to be given a name that "would give it its purpose, its function, its identity." And his master ends up naming him "Dog" of all things. At the exact instant when the hell-hound receives this name, he is permanently changed, and much of the evil within him is extinguished, a process which will continue little by little through the end of the world.
Now, as I've stated before, I believe the main message of Good Omens is that our individual choices define who we are. If this is the case, and I think it is, why would Neil Gaiman and Terry Pratchett create a character who is unwillingly molded into what he ultimately becomes: a normal dog and man's (well, "boy's" actually) best friend?
I think that Dog is really meant to show the ability of anyone and anything to be redeemed, especially by the power of innocence. I know that sounds a bit trite, but bear with me here. Dog is sent to earth as a hell-hound, a pure-bred evil canine from the fiery pits of the Inferno whose purpose is to serve the Prince of Darkness in carrying out dastardly and devilish deeds of discord. However, in being named Dog by his master, that becomes his purpose: to be a just a regular dog. Adam was raised with no knowledge of his true origins, thinking himself the natural product of Mr. and Mrs. Young. He's just a normal boy, and through coming into contact with Dog, he is able to turn Dog from a evil hell-hound into force of good. Perhaps this is meant to show that through the power of good and pure intentions, even the most vile creature can be turned into something decent and wholesome.
For more on this "Nature vs. Nurture" concept, here are the other blog posts:
"Nature and its Role", by Lauren at Writers Lost (Group 3)
"Nature vs. Nurture in Good Omens", by Merideth at Writers Lost (Group 3)
"Where English meets Psychology", by Sarah at Forbidden Fruit (Group 4)