Faulkner's novel is roughly based on the biblical story of David and Absalom. The background to this story is that King David arranged to have a close friend killed in battle so he can marry his wife Bathsheba, whom he had impregnated. Because of David's sin of arranging the killing of an innocent man, the prophet Nathan states that David's family will be cursed by infighting and hatred between family members.
This comes to pass when David's beloved son Absalom kills his brother Amnon for raping their sister, Tamar (Tamer is Absalom's full sister and Amnon's half sister). Absalom flees and, because he is young, charismatic, and popular, ends up leading a civil war against his father. His beautiful, long hair gets tangled in a tree and while he is dangling, he is killed against David's orders. David is very grieved by the loss of this son.
The story Faulkner tells takes its inspiration from the biblical story, but is not an exact replica. However, it is about a patriarch named Sutpen who, like David, comes from nowhere to build an empire, is stained by sin (in Sutpen's case, racism), and ends up with two sons caught in an incest triangle that leads to the Absalom figure, Henry, killing his half brother Charles, and later dying in a fire.
Faulkner calls his novel Absalom, Absalom! as an allusion to the biblical story. The repetition of the name shows how tragedy repeats itself throughout history, with the sins of the fathers being visited on the sons.