If "Elohim" can refer to angels and demons, then does Jesus being called "God" really prove anything? In arguing for the Trinity, I mentioned that Jesus was called God (Theos in Greek). The rebuttal was that Theos in the Greek is equivalent to Elohim, which can refer to angels, demons, or just about any spiritual including God. Is there a good refutation to that argument?
Great Question! Arguing for the trinity is one of the most complex apologetic tasks you can undertake. 

Context is essential to understanding the meaning of any word, especially in Semitic languages (e.g. Hebrew/Arabic) since the same word can have several connected but different meanings. Your questioner seems to be using a faulty analogy since the words are not precisely identical in meaning. Consider challenging with counter questions.
Suggestions for greater clarity:


Consider focusing your question in terms of specific verses - in context, some are clearly referring to angels and others have always been interpreted by Christian and Jewish interpreters as referring to 'God'. Does your interlocutor genuinely believe that the use of 'Elohim' in Genesis 1:1 is referring to Angels (contra millennia of interpretive tradition)?
There is a vast difference between saying that a word can be 'translated' one way and saying it is perfectly equivalent. The Holy God of the bible is not easy to understand and is never fully known (see doctrines of divine simplicity etc.) so the words used in various languages for 'God' are always approximations apart from God's use of his own name. For example, Elohim is plural whereas Theos is simply a generic word for god (not necessarily 'God'). Does your opponent believe that the generic use of 'man' CANNOT we used to refer to humanity (men and women)? If they have not difficulty with that, it shouldn't be difficult to understand how the word for 'strong one' can refer to both angels and God in different verses.


Conclusion: Just as a woman can say she is a member of man-kind to declare that she has the dignity due to all humanity, so Jesus can use Theos/Elohim/God to declare that he is worthy of being worshiped as Creator and Sustain-er of the world.

Some background on the terms themselves: http://embracedbytruth.com/God/Names%20of%20God/Elohim%20and%20Theos.htm