Are there any truths in the Bible?  The Koran (Qur'ân)?  The Holy Scriptures of Judaism?  While these writings are obviously filled with mythology, fabrications and exaggerations - it is likely that there is an element of truth in many stories with respect to some people and events.  Unfortunately, many of these stories have been stretched and embellished to the point of being laughable (See Science, Truth and the Church and Thomas Paine's "Age of Reason".)  However, the fact that references to the story of Abraham, Sarah, Isaac & Ishmael appear in all three of these religious documents lends some credibility to portions of the historical account.  One can build a somewhat cohesive overlap between the Bible, the Koran and the Holy Scriptures of Judaism, with respect to their lineage and origins of belief.

"As you will see, the origins of these three religions are a result
of family feuds, tribal divisions, mistresses and concubines." 

The story begins with Abraham (the Bible refers to him as Abram and later Abraham, Koran refers to him as Ibrahim).  Abraham was supposedly chosen by God to spread his word and rule a great nation.  Abraham was married to Sarai (or Sarah).  However, Sarah was barren and unable to have a child to lead the great nation.  So, she told Abraham to have sex with their Egyptian servant Hagar in an attempt to have a child.  Hagar conceived and Ishmael was born.  However, later Sarah did ended up having a son with her husband Abraham.  This son of the marriage was Isaac.
 

Jews, Christians and Muslims all consider themselves as Abraham's spiritual offspring.  However, the division of Abraham's message into separate religions was a direct result of the two sons - one born in marriage to Sarah, the other to the Egyptian servant Hagar.  Muslims claim the first born son, Ishmael, was an apostle and prophet, and was the legitimate successor.  Christians and Jews believe it can only be the son resulting from conception within the marriage, or Isaac.  Jews believe further that their divine message comes not only from Isaac, but from Isaac's son Jacob.

According to all 3 scriptures (the Bible, the Koran and the Holy Scriptures of Judaism), God calls upon Abraham to sacrifice his son as the greatest test of faith.  However, in the Christian and Jewish Bibles, the son chosen to sacrifice was Isaac.  Muslims believe it was Ishmael.  (Note: Neither son was actually sacrificed because God was just practicing a cruel test.  In the end, a ram was sacrificed.)

From these original family feuds, the division between the religions continued to deepen.  Christians follow the teachings of Moses, Jesus and Abraham.  In Islamic religion, Muslims believe the Prophet Muhammad in the seventh century carried the true word.  They believed the teachings of Moses and Jesus to be distortions of the truth for which Muhammad was the remedy.  Jews continued their split from Christianity by not accepting the divinity of Jesus as "the son of God".  They believe God is spiritual, not flesh, and has no human attributes.  Jews also do not believe in original sin nor heaven and hell.

Sex: The twisted sexual story of Abraham, Sarah and their slave mistress Hagar is an interesting one.  However, there's more.  Prior to having Isaac and Ishmael, Abraham and Sarah traveled to Egypt.  Sarah was very beautiful and Abraham feared that the Pharaoh may kill him to take his wife.  So, Abraham told Sarah to say that she was Abraham's sister to save himself!  The Pharaoh was interested in Sarah and she became one of his concubines (or wives).  Later the Pharaoh discovered the deception and banished them both from Egypt.  Sounds like a juicy smut novel, but the Bible is full of this type of stuff!

Age: We are told that Abraham was 90 years old when Ishmael was born and 100 years old when Isaac was born.  Isn't it doubtful that a man of this age could be so successful spreading his seed?!  Even more questionable, Sarah was supposedly 90 years old when she gave birth to Isaac!  Now, I'm sure you find this as hard to believe as I do!?  According to the Bible, even "Abraham fell facedown; he laughed and said to himself, "Will a son be born to a man a hundred years old?  Will Sarah bear a child at the age of ninety?" [Genesis 17:17].  Also, Sarah "laughed to herself as she thought, "After I am worn out and my master is old, will I now have this pleasure?"

Populations: Today, the tribal division that resulted from Abraham's sons has resulted in: 

• 1 billion Christians, 
• 1.2 billion Muslims, and 
• Nearly 15 million Jews.