They have a son, Cain; (and later his brother Abel).
There's the feud between them, Able dies, and then:
Cain goes out to the city, and gets married!
Where the fuck did a city come from?
Where the hell did his wife come from?
There are three people who exist - Adam, Eve, and Cain.
Who built the city? Is the wife his sister? Was God making people out of dirt all over, and they just didn't mention it? Whose rib did this new chick come out of?
Obviously anyone who takes Creationism seriously, or who takes the Bible literally, is either illiterate, or a complete fucking moron!
Oh, wait, no wonder they re-elected Bush!
It all makes so much sense now.