The most important factor in Islam's contribution is its concept of monotheism – of there being only One God (2:163). According to Islam, God, or the Ultimate Reality of this universe is only one called God in Islam. It is implicit in the concept of the Oneness of Godhead that differences and multiplicity would appear to exist in reality, yet there is an underlying unity.
In this way the concept of divine unity engenders spiritual unity. All human beings are one, because they are the servants of One God. All human beings are God's family. God is indeed the greatest reality of the universe. And when it is acknowledged that there is only One Greatest Reality, it is but natural that all other creation should acquire the character of unity.
God in actual fact is not many. God is One, Eternal and Absolute. He is everything, everything is from Him. God, the Creator of all things is the Sustainer of the universe. All depends upon him. He depends on none. He, in his own being, is all-powerful. He is above to ‘beget’ or ‘begotten’. He is such a unique Being who has no equal or compare. All kind of oneness belongs to this Almighty Being.