Seth, the Sons of God, and the Daughters of Men

In Genesis chapter four, at the very end, it said that adam knew his wife again. And she gave birth to another son, whos name was seth. There's two kind of distinct threads of humanity that come off of this. The canite line, rite kane, because he's still alive, and the sethite line, seth, because he is alive. But what happens is, ahm, there is a distinction that's made in chapter six that is very, very complicated for us. It says, the ah sons of god, saw that the daughters of men were fair, they took to wife such of them as they chose. What does that mean