I also find it humorous when a Trinitarian actually tries to use this argument.
Elohiym (or Elohim) literally means God (Singular) or gods (plural). So if a Trinitarian seriously uses this argument he/she would be implying that there is more than one god. It in no way shape or form promotes the idea that there are multiple persons within a singular God. It promotes multple gods. (if you would use the plural argument).
Trinitarians also use the plural language He used (when He spoke to Himself) ) (ie: "Let Us make man in Our image"). This argument would only hold, if it was consistant throughout scripture, but it's not. I am the Lord your God (elohim), who brought you out of the land of Egypt, out of the house of slavery; (3) you shall have no other gods (elohim) before me.[/u]
Notice several things.. First off the singular terminology He used. "I" (not "we") and "me" (not "us"). God was very clear in this commandment. He is the ONE God you are to serve. And yet notice the exact same word is used for both the ONE God (elohim) and the plural false gods, (elohim).
The elohim argument simply doesn't in anyway support trinitarianism. At best someone could argue that there is more that one god (which is polytheism), but even that idea is destroyed throughout the Bible.
BTW, the Jews have been reading the old testament (the Torah) in their own language, in their own culture for thousands of years.. Yet they have never once come to the conclusion that God is multiple in persons, or that he is plural. They've been reading Genesis for much longer than we have, and they've held true to the biblical monotheistic message described throught the Bible. (Duet 6:4) "Hear o Israel, the Lord our God, the Lord is One."