Christianity predates islam.
Instead, the word "Allah", as a lot of other words, especially words of the religious sphere, was imported from the Syriac (Aramaic) language: "alaha" - with three long a-vowels -, is the Aramaic word for the (Christian) unique God. The last (long) "a" characterizes the status absolutus in the Aramaic language and was duly omitted by the Arabs like case endings in the Arabic vernacular, whereas the understanding of the first syllable of "alaha" as an article was a common misunderstanding like for instance in "al-Iskandar" from Greek "Alexandros" etc. The doubling of the "l" is irrelevant, since the doubling sign is a very late invention of Arabic orthography, centuries after Muhammad.
The Origin of the name "Allah"
The muslims, who came later, adopted the same word. Today, christians are being punished for using a word that derives its origin from the Syriac Aramaic language spoken by Jesus.
Malaysia’s Highest Court Upholds Ban on Christians Using the Word Allah
The English word we use is "God". Suppose you were told that you could no longer use this word in prayer. You could continue to use Lord but not God. Consider the impact on your prayer life.
Not the question. Judaism pre-dates Christianity. It is a non-sequitor. The language is the question. Arabic and Hebrew have the same root, Abraham who learned to speak in Ur of Chaldea.
In other words, more Muslim stealing.