No. We should not believe in anything unless we have identified facts in reality that prove it is true. The fact that the hypothetical alien race you ask about is technologically superior to us does not prove (or even suggest) the existence of their god. The premise behind your question appears to be a logical fallacy: the appeal to authority. Essentially you are saying, "hey, they are really smart and they believe in this god, so we should too."
Objectivist ethics holds that rationality is the primary virtue. This virtue requires using reason as one's only source of knowledge, and the rejection of all arbitrary or mystical claims to knowledge. Independence is another virtue of the objectivist ethics, which requires, among other things, that one strive to understand reality oneself rather than accepting allegations "second-hand" from others. For these reasons, and many others I have not listed, Objectivism rejects appeals to authority.