Without Abraham as a portal figure the three monotheistic religions would presumably fall. However, imagine Abraham as a totally fictitious person based on the Hindi concept of Brahm (Parabrahm) - the creator who transforms himself into other gods and the entire vision of the Universe and, that Brahm sometimes would be Brahmam, just like Abraham sometimes would be found under the name of Abram. Also, since Abraham was made forefather of many peoples ”And I will make thee exceeding fruitful and make nations of thee” (Gen. 17:6). Wasn't it in fact to be expected - probably for the most noble of reasons - that monotheistic worshipping would lead to peace between peoples and that just the plural form ‘peoples’ would lead to a general belief in the faith of the Hebrew creed of one God through a common forefather Abraham?Imagine that a crowd of wise men somewhere in Babylon, during the first Millennium BC, presented this new road for mankind.
Power of Goodness 
Brahm and Abraham
They founded concepts of thousands of years of experience, and gathered these into one piece of writing, calling it the ”Torah” or the Old Testament and like benevolent reformers, considered giving re-birth to the idea that God is ONE and invented someone called Abraham as their spokesman, thus trying to reach back to the original concept of the Creator as ONE. They dismantled the degenerative process that so far had brought to light numerous and in same faiths millions of gods. It was a quest to reveal the true God, the spiritual code for human coexistence, naked without the subversive garment of human add-ons that so far had diluted the Idea and brought misery to mankind. But the proclamation of the Jews as God's chosen people laid the foundation to expressions of Jewish arrogance, easily understood from the shabbat blessing where Jews talk about themselves as chosen by God and sanctified among all the people of the world.