Although your question is a good one, the answer to the question actually is not all that easy without being simplistic. The fact is that Thayer’s is about as good a Greek-English lexicon, one numerically indexed and available, for study without a need to know a lot of Greek. For those who are able to work with Greek, the Greek-English lexicon by Liddell & Scott is much more comprehensive. However, for this particular passage, neither will be much help in answering your question.
In order to answer the question, one has to begin with monotheism, the foundation of biblical faith. There is just one God. From that foundational fact, one has to then develop the rest of their theology accordingly.
In that regard, I want to direct you and our readers to the Encyclopedia Judaica, Volume 5, p. 1521 ff. This is an excellent treatment on the whole historical development of devils and demons. You will note that in none of the languages of the ancient Near East, including Hebrew, is there any general term equivalent to the English word, demon.
In the Old Testament, their mention is practically nil. In the New Testament, their appearance in part reflects influences of Zoroastrian Dualism and Greek and Roman Mythology. Additionally, I would refer you to the Encyclopedia Judaica, Volume 14, p. 902, to the entry Satan and the statement, “Satan is not a proper name referring to a particular being and a demoniac one who is the antagonist or the rival of God. He is identified with the ‘yetzer harah’, or the evil inclination. See also my article here, Of Devils and Demons.
Although many of the Epistles, especially those of Paul, were originally written in Greek, they were talking about Hebrew things, Hebrew ideas.
Reading this text in Hebrew and taking everything else into consideration, it seems clear that ‘elohay ha olam hazeh’ is referring to God mentioned in Verse 2. God is the one who has blinded the minds of the apostate unbelievers, just as he hardened Pharoah’s heart
