The Language of God in History, Chapter 4 Excerpt, "Origins of the Nephilim"

One of the reasons why some people believe that Eve had sexual relations with the Devil is the fact that Cain was so unrighteous that he murdered his own brother in cold blood a sinful behavior people readily equate with Satan. However, the Bible makes it clear that Adam and Eve were fallen and sinful from the moment they rebelled against God. In fact they even lied to God and blamed one another and the Serpent when they were confronted by God with their sin. These actions were clearly unrighteous, and there is no reason to think that Cain and Abel were born with any less of a propensity to sin than their parents! In fact, the whole concept that mankind is essentially born innocent and good is erroneous. As a parent, I have seen the evidence of sin in my own sweet daughter before she was even a toddler, and the Word clearly teaches that: “no one is good but One,” and “for all have sinned and fall short of the glory of God” (Luke 18:19; Romans 3:23).