The "Cultural Context" Excuse

[Thumpalumpacus]

Here is your first clue.

Genesis 3
14And the Lord God said unto the serpent, Because thou hast done this, thou art cursed above all cattle, and above every beast of the field; upon thy belly shalt thou go, and dust shalt thou eat all the days of thy life:
15 And I will put enmity between thee and the woman, and between thy seed and her seed; it shall bruise thy head, and thou shalt bruise his heel.

The clearly states that the serpent had a seed (which Eve was already pregnant with).

Except, it doesn't say what your parenthetical statement says it does.

Your second clue.

If you read the genealogy (which traces the bloodline of the firstborn male heir) of Adam, you'll notice that Cain (who WAS the firstborn) is not mentioned as Adams son.

Genesis 5
This is the book of the generations of Adam. In the day that God created man, in the likeness of God made he him;
2 Male and female created he them; and blessed them, and called their name Adam, in the day when they were created.
3 And Adam lived an hundred and thirty years, and begat a son in his own likeness, and after his image; and called his name Seth:
4 And the days of Adam after he had begotten Seth were eight hundred years: and he begat sons and daughters:
5 And all the days that Adam lived were nine hundred and thirty years: and he died.

So, does it say that Cain's father was the snake?

No, no it doesn't.

Your third clue.

1 John 3:12
Not as Cain, who was of that wicked one, and slew his brother. And wherefore slew he him? Because his own works were evil, and his brother's righteous.

*empasis mine*

You will never find anywhere in the bible where it states that Cain was Adams son, you guys just ASSUME it to be so.

Is there a reason why Adam cannot be "that wicked one?"