Another quote from Lesley Hazleton’s The First Muslim, “As historian James Carroll points out, the Jewish scribes who actually wrote most of the Hebrew bible during the sixth-century BC Babylonian exile conceived of “one god” less as a specific identity than as an affirmation of unity. The personified Yahweh, the territorial god of Israel, gave way to the ineffable Elohim, the universal god—the same god known in Mecca as al-Lah. In this older and wider concept of monotheism, says Carroll, ‘the God of this people is the God of all people, associated not with a clan or a tribe or network of tribes, but with all that exists.’ God thus becomes ‘the reconciliation of all oppositions.’”
Hazleton shows how Muhammad used the idea of the one God to break down tribal unity with their own gods in order to unite the different Arab tribes and even some Jews under the one God
Historically Speaking 