Your statement about not even uttering God's name brings up a very interesting point. There are Eastern and/or Mystic concepts that say the word is not the thing. And it refers to people using words so much and categorizing things, that things that are actually unique are not seen for their uniqueness and instead are seen in terms of their category or the word that one has for it. Transcendentalism also says something similar, where a tree is not really a tree or a tree is not really the concept we have for it, and it's existence and essence is actually something completely independent of our ideas for it. Krishnamurti had an interesting thing to say when he said the moment the child learns the name of the bird, that child will never see that bird again. Despite similarities that things have, everything is actually unique and there are no two identical creatures in nature. So the child will not see that unique bird, he will see his preconceived category for it based on the word he has for it.<quoted text>
What vain means is pretty subjective some may agree with what you said some others may take a more extremist view after a rationalization over that commandment. The latters are the Jews who thought that the name of their lord is too holy that an human being is not worth of pronouncing for any whatsoever reason, hence they avoid to put vowels when they write its name or to avoid to pronounce its name at all, they started to use nouns like hashem (the name), adonai (our lord) etc.
So words can be helpful, but they can also throw you off the track, especially if we are talking about an abstract notion such as God. So what was alarmingly interesting about the Jewish concept for God is that God did not give them a name for him, as that would then lead them to have false notions for God or to put God into some sort of category. God identified himself in the most core way that one can by simply calling himself "I am". So if the whole thing is made up and fictional, I found this to be alarmingly wise for the author to choose God as not giving himself a name. It's things like this that make me think twice before I say that the whole thing is nothing but a fairy tale, as you might believe. I wouldn't see an author who is simply making things up being this wise and deep.