The Arabic word for “God” or “deity” (common name) is إله pronounced as “ilah”. The proof that this is the common word for any deity is found in the Quran, Hadith, pre–Islamic Arabic poetry, Arabic Bible etc. In all these sources, the word إله is the word used for any deity.
On the other hand, the word الله (Allah) is PROPER NOUN, the name of the Creator of the world alone. The proof for this is that besides the Creator none was ever called الله throughout the history of Arabia in any Arabic source. In other word, no idol or any deity was ever called الله in history – only the Creator of the world is called الله in every source you can lay your hand on.
If الله were common name for deity, idols should have been called by this name from pre-Islamic times. But no idol was ever called الله in history. Only the Creator of the world is called الله in the Holy Quran, in Hadiths, in pre–Islamic Arabic poems, in the Arabic Bible etc.
Therefore, the Arabic word for deity in common has ever been إله (Ilah) while الله (Allah) is just the Arabic proper name of the Creator which is never used for any other deity.
Since before Prophet Muhammad was born, Arab Jews recognized this fact and have been calling the Creator as Allah in Arabic.
In Hebrew = Yahweh
In Arabic = Allah
They called Allah as their father in both their Arabic Scriptures and in their worship.
You should note that the Jews never mean God is their literal Father whenever they call him “father”. They used the word “father” for God only figuratively, meaning that God is their source (potter, creator): –
“But now, O LORD, you are our Father; we are the clay, and You are the potter; we are all the work of Your hand.” (Isaiah 64:8)
Arabic language has nothing like this figurative use of “father” which explains why God is never called “father” even figuratively in the Quran. But the Quran accepts the meaning of this Jewish figure of speech that God is our source and creator.
So, the figurative use of “father” says nothing negative about Islam since Islam accepts the meaning of this Jewish figurative term.
The Quran only rejects God being literal Father of anyone which no Jew ever believed in.
Arab Jews Christians pagans hanifs worshipped same God. (Allah)
Before Prophet Muhammad was born, there were the following religious groups in Arabia:
1. Arab Jews such as Banu Qaynuqa, Banu Quraiza etc.
2. Arab Christians such as Arab Christians of Najran.
3. Hanifs — Arab monotheists who never worshipped an idol but were not Jews or Christians.
4. Pagan Arabs who claimed to worship the true God through idols.
★ pagan arabs worshipped many idols besides Allah.
Same as Christians worship Jesus and Ghost besides father.
But there is One God. Who was no partner.
Allah knows Best