Brother, I understand where you’re coming from, but I have to disagree. God did not begin with the Jews. The Jews were chosen for a specific mission, yes, but the One God created the universe, and indeed existed before Abraham, before Moses, and before the nation of Israel. He is the Creator of Adam, Noah, Abraham, Isaac, Ishmael, Moses, Jesus, and Muhammad, peace be upon them all.
Being a descendant of Abraham does not make someone automatically right with God, and not being a descendant of Abraham does not make someone worthless before God. In the Bible itself, God is shown as the God of all nations, not only one people. The prophets repeatedly called humanity to worship the same One God.
If worship were only valid for bloodline, then faith, repentance, and obedience would mean nothing. But the whole message of the prophets is the opposite: God judges people by truth, sincerity, and submission to Him, not by ethnicity.
So no, Islam did not “steal” God from the Jews. Rather, it calls people back to the same eternal God worshiped by Abraham and all the prophets — before any religious nation, before any tribe, before any division among mankind.
The real question is not who can claim descent, but who is truly following the One God who created us all.
As Salaamu Alaykum!
