In Biblical accounts, Cain was one of the sons of Adam and Eve. He was the first murderer in the world.
Cain and AbelEdit
According to Genesis, following humanity's fall, Adam and Eve eventually had two sons: Cain and Abel. God had shown favor to Abel, who sacrificed his best lambs to God, while Cain merely offered some typical crops (showing disrespect towards God as a result, as Cain did not offer his best to show his devotion). God accepted Abel's offering while rejecting Cain's. In an envious rage, Cain slew Abel in a field. Later on, God spoke to Cain, and revealed that he knew of this murder. God decreed that the ground would not produce for Cain, and that he would exist in a state of perpetual wandering. Cain responded that the punishment was too great and that anyone meeting him would kill him. God responded by marking Cain, saying that anyone who slew Cain would have sevenfold vengeance taken on him. Cain then departed, heading to the land of Nod, which is east of Eden. It should be noted that the Land of Nod is not an actual place, but rather a state of wandering, as Noded means wander in Hebrew.
Cain and KaneEdit
With the pseudo-religious nature of the Brotherhood of Nod, one can not escape the similarities between the name of Nod's leader with Cain. While the name could be coincidental, it could also be that Kane is using the name to boost his image as a prophet. However, there are some who believe that Kane is also the Biblical Cain. These people also believe that this makes Kane immortal. This concept would explain Kane's agelessness, as well as why he would survive several lethal blows (Notably, the Ion Cannon strike on the Sarajevo Temple of Nod).
Artifacts found in a cave below a Nod facility indicate a possible link between the Brotherhood and this legend. Whether Nod really is thousands of years old or they just named themselves after the 'Land of Nod', to which Cain was banned after the murder is unknown. However, no concrete information is yet known regarding this matter, particularly since the Temple where this was found was completely destroyed by the detonation of a nuclear bomb.
Seth, Kane's second in command during the First Tiberium War, would be another reference to Cain, as his brother was also name Seth. The Marked of Kane presumably draw their moniker from the biblical mark of Cain.