Sorry for the delay...

I was (and still am) planning on responding to your first post, but you sufficiently provoked me to respond to your second post. I don’t think the question you raise (which many people ask, and many atheists like to advocate- though I'm certainly not accusing you of this, since I know you're just playing devil's advocate) should not anybody. Of course it is true that given the current makeup of the human psyche, humans could "create" the idea of God, for the reasons you mentioned. However, that is irrelevant to the question of whether or not God exists. The idea shows that given a theoretical universe where God doesn't exist, the existence of the "God idea" in people's minds could be satisfactorily explained psychologically. It may prove that the fact that humans have the concept of God can not alone prove that God exists (although most versions of St. Anselm's ontological argument probably still hold up against this question… even though they mostly don’t hold up in general). But contrary to the writings of some of the popular atheists (and by popular I imply both meanings of the word) it certainly does not negate the notion of God's existence. One could easily believe that the idea of God could have been made up, but it happens to not be made up, since He exists.

Furthermore, the idea that humans could conjure the idea of God may also be a result of the human soul, which has a longing for meaning (assuming we have a soul, which is assuming God exists). Therefore, the idea that “God was created by humans may only be relevant if one is already assuming that God does not exist. There is no contradiction in believing in God, and also believing that humans could have made up the idea of God. Just like some of the things we discussed last Shabbos, this is all an issue of perspective.

A parallel to this that we already talked about is Bible criticism. The documentary hypothesis shows that given the theoretical situation that the Torah was written by several authors, we could figure out how to read the Torah accordingly. This does not pose a direct contradiction to the notion that God dictated the Torah. In other words, one could easily believe that the Torah could be read as if written by four authors, but still believe that it doesn’t have to be, because it was in fact written by God/Moses. Therefore, the documentary hypothesis is not related to the question of whether or not God wrote the Torah.

Another parallel is the argument about evolution. In order to "save the Torah," some people will claim that all of our evidence for evolution was planted by God in order to test our faith. This is silly, but it can't be disproven by any amount of evidence. Therefore, belief in evolution is also a question of perspective.
However, unlike Bible criticism one can fully believe in Torah and also in evolution, because they especially do not conflict for many reasons (I actually wrote a whole article about this in YU's Jewish thought magazine). Evolution is also different than the documentary hypothesis since it has hard scientific evidence.
A relevant anecdote I was told by a Rabbi/Professor (I would use names, but should I on the internet?): A Rabbi/biologist was discussing evolution and saying that the theory that God planted evidence of evolution to test our faith is not something that God would do. A Bible Professor chimed in, “Then why did God make the Torah look like it has four authors!?” (Note: everyone in this story accepts evolution and does not accept the documentary hypothesis)

Combining both of these topics again, another Rabbi/Prof likes to joke that the debate about the authorship of Torah is one large proof of evolution, because each side has adapted their position to such an extent that they will be able to incorporate any evidence thrown at them by the other side into their own view. In other words, any ‘evidence’ mentioned by Bible critics about different styles of writing, or even duplicate stories is understood by traditionalists to be a manifestation of the complexity of God and his Torah. And any time the traditionalists will throw a verse at the Bible critics that seems to not fit within their hypothesis, they will simply respond that it was added later, or for stylistic reasons, etc.

To summarize, all of these are issues of perspectives, and therefore not really bothersome. If one assumes God can’t write or talk, or assumes miracles or prophecy are impossible, then he can make sense of the Bible through Bible criticism. Without the perspective of those assumptions, the documentary hypothesis is just another alternative reading that is not any more compelling (maybe even less compelling) than the traditional view. Also, if one wants to assume there is no God, then he can explain the ‘God idea’ through psychology. Without that perspective, the conjuring of God by humans is just a theoretical alternative to what actually happened: that the God idea exists because God Himself exists. Since both of these are issues of perspective, it is almost by definition that neither side can ever disprove the other side, whatever evidence they bring. Therefore, the two sides are not in direct conflict.