In Genesis Chapter 15 verse 5 we were told God asked Abraham to count the stars because that would be the number of his seed (children) and that promise began in Genesis 16 verse 15 Hagar bare him a son Ishmael. Now in Genesis 21 verse 2 Sarah bare him a son, Isaac. These has been one of the greatest stories ever told in my opinion. In Genesis chapter 21 9-21 Hagar and her son Ishmael were driven out of Abram's home but we are told he survived the desert and prospered. Now I don't have access to the Koran but Abram is also in the Koran (so I've heard) and it's believed that Islam came out from Ishmael and Christianity/Jew from Isaac. There are also Prohets (Moses etc) that appears in both Holy Books. Now my point is can we say both Religion originated from thesame source and could we say both are like half-brothers or something. Now the thing with half-brothers and family you'll always fight yourselves but understand you share same father/mother. So I want the Muslim scholars and Christian scholars to explain this further.
P. S: No abusive words or condemning anyone to Hell/Jahannam.

Ishmael was the bastard child of Abraham.

Ishmael also started Islam.

If only there was condom then.