At the risk of upsetting folks, I would like to come to the defense of Theophilos.
I don't speak Arabic, and therefore, don't really know the history and use of the language.
However, the use of Allah as God, rings hollow in my ears. Yes, this may be because I am not the one saying it. However, I am surrounded by Arabs. When I visit either of the huge Antiochian churches in my area, I have never heard the use of "Allah"....ever. Lots of Arabic words thrown around, but, never Allah. This may be because the services I attended were mostly in English, because they knew a mixed crowd was coming. I don't know.
However, I work with a good number of Arabs, and they are all Muslim....and use Allah every 5 minutes. Allah this, Allah that, Inshallah, ...
I turn on the news and I see all the violence done in the world in the name of Allah.
So, to me, Allah actually is rather chilling, and does not bring peace to my heart.
Having said that...I completely understand Arabic people sticking to their own language, as I prefer Ukrainian to anything else....and I would be the last person to stop someone praying in their own tongue.
However, many "Faith" based words, are not in my mother tongue....even when said in "Ukrainian". We have Літургія - Liturhiya - Liturgy. Definitely with Greek origins. Iconostas, solea, amvon, etc.
We have many words that we use that are not of our mother tongue when it comes to God.