Right.... unless you're an Arabic-speaking Christian. Arabic Christians have more historic "right" to use this word than Muslims do, since Arabic Christians were using the word "Allah" for 500+ years before the birth of Mohammad, ever since the Apostle Paul preached to the Arabs in the first century AD (Ref: Galatians 1:17 "...I went into Arabia, and returned again unto Damascus.")
Ten million Arabic-speaking Christians use the Arabic word for "God," which is "Allah". You probably use it too. It is found in the word "alleluia"
I agree as to the first part: In attending Divine Liturgy at an Antiochian Orthodox parish some years ago I heard a communion hymn that seemed to reflect the use of that Arabic name.
That said, I thought the etymology of alleluia was as described here, but I am not an expert.