Origin of Allah

Etymologically, the Arabic word Allah is the contraction of two Arabic words: al (the) and ilah (god). The word Allah (the god) has been in use among Arabic-speaking Jews, Christians, and even pagans from pre-Islamic times. Its general meaning is “supreme god,” but each group employed it as a part of their religious terminology by attributing their unique understanding of the concept of God to the term.

For Arab Jews, it is the same as El (Hebrew: God) or Elohim (Hebrew: God/Gods). For Arab Christians, it is the same as Theos (Greek: God). This understanding is clearly reflected in the Arabic Bible, which combines the translations of the Old Testament (O.T.) and New Testament (N.T.) from Hebrew/Aramaic and Greek into Arabic.

It is significant to note that although the word Allah is used in the Arabic Bible, it was never used in place of the name of God i.e. YHWH (YaHWeH), as given in Exodus 3:14. This personal name of God is also used in the Bible in its short form, YAH, several times. In the Arabic Bible, the word Rub/Rabb (Lord) is used instead of God’s name, YaHWeH or YAH.

The God who revealed Himself to and interacted directly with the prophet Moses (Musa) made it abundantly clear what His personal name is. Upon the prophet Moses’ insistence, God proclaimed His personal as well as preferred name as YHWH [יהוה], which emphasizes His unchanging, eternal self-existence as ‘I AM.’    

The Almighty God reiterated his personal name through the true prophets: 

Prophet Musa (Moses): “Moses said to God, “Suppose I go to the Israelites and say to them, ‘The God of your fathers has sent me to you,’ and they ask me, ‘What is his name?’ Then what shall I tell them?” God said to Moses, “I am who I am. This is what you are to say to the Israelites: ‘I am’ has sent me to you.’” (The Bible-Exodus 3:13-14) 
Prophet Dawood (David): “Let them know that you, whose name is the Lord (I AM) that you alone are the Most High over all the earth.” (The Bible-Psalm 83:18) 
Prophet Ishaya (Isaiah): “For your Maker is your husband the Lord (I AM) Almighty is his name the Holy One of Israel is your Redeemer; he is called the God of all the earth.” (The Bible-Isaiah 42:8) 
Prophet Irmiya (Jeremiah): ““Therefore, I will teach them this time I will teach them my power and might. Then they will know that my name is the Lord (I AM).” (The Bible-Jeremiah 16:21) 
Prophet Hizkiyal (Hezekiah): “And so, I will show my greatness and my holiness, and I will make myself known in the sight of many nations. Then they will know that I am the Lord (I AM).’” (The Bible-Ezekiel 38:23) 
Prophet Husha (Hosea): “The Lord God Almighty, the Lord (I AM) is his name!” (The Bible- Hosea 12:5) 
Prophet Amus (Amos): “He who made the Pleiades and Orion, who turns midnight into dawn and darkens day into night, who calls for the waters of the sea and pours them out over the face of the land the Lord (I AM) is his name.” (The Bible-Amos 5:8) 

In contrast to the prophetic tradition mentioned above, the Quran—along with Muhammad in the hadith—fails to refer or allude to the personal name of God as revealed in that tradition.

For Arab pagans, Allah referred to the highest god over the pantheon of gods and goddesses they worshiped. Finally, from the seventh century onward, Muslims began to define the word based on how they understood God through the teachings of the Quran and Hadith. By the twentieth century, Muslims had largely popularized the word Allah as the proper name of God across the globe, despite the fact that the word is still used in a generic sense by Arabic-speaking Jews and Christians.

According to Sunni Islamic scholar Ibn Kathir, the pre-Islamic pagan Arabs used the word Allat as the feminine form of Allah.

Interestingly, nowhere in the Quran God says, ‘Allah is my name’ or ‘My name is Allah’ except saying ‘I am Allah.’ The statement ‘I am Allah’ can be understood as ‘I am the god.’ Neither ‘God’ nor ‘the god’ is the proper name, much less the personal name of the Creator. The reason for the absence of clarity in this significant area is either because the writer of the Quran did not realize its importance or because it did not occur to him at all.