Cain killed Abel
We have just witnessed the first murder.
Cain, the offspring of that old serpent, the devil, Satan
himself, brutally killed Abel,
the first son of Adam, a righteous man.
It was that "wicked one's" second attempt (this time through
to destroy the woman and her "seed" through which Jesus Christ, the Messiah would be born.
And since Cain was not Adam's son,
God would have to raise up another to fulfill His plan.
Verse 25 of this same chapter documents that He did,
and so Seth replaced Abel in Christ's ancestry.
Gen. 4:25 And Adam knew his wife again; and she bare a son, and called his name Seth: For God, said she, hath appointed me another seed instead of Abel, whom Cain slew.
That enmity God said would be there in Gen 3:15 is a sure thing.
God's Word is always true.
The word "Cain" in Hebrew is "Kajin", spelled with a "K", and so his children are naturally called Kenites, a transliteration (which is basically a letter to letter conversion) from the Hebrew to English. Look up the word "kenites" in a World Book Encyclopedia Dictionary. They are defined as the children of Cain (Kain-ites).
It was the kenites who were responsible for the murder
of Jesus Christ,
though Judah has taken the "rap" because of the ignorance of the unlearned.
It was the kenites, beginning with their father Cain,
the first murderer,
who killed the prophets and righteous men of God.
And guess what?
Christ called them "serpents" and "vipers".
Where have we heard that terminology used before?
In the garden, of course!
And they are a bunch of snakes.
Matthew 23:29-35 Woe unto you, scribes and Pharisees, hypocrites! because ye build the tombs of the prophets, and garnish the sepulchres of the righteous,  And say, If we had been in the days of our fathers, we would not have been partakers with them in the blood of the prophets.  Wherefore ye be witnesses unto yourselves, that ye are the children of them which killed the prophets.  Fill ye up then the measure of your fathers.  Ye serpents, ye generation of vipers, how can ye escape the damnation of hell?  Wherefore, behold, I send unto you prophets, and wise men, and scribes: and some of them ye shall kill and crucify; and some of them shall ye scourge in your synagogues, and persecute them from city to city:  That upon you may come all the righteous blood shed upon the earth, from the blood of righteous Abel unto the blood of Zacharias son of Barachias, whom ye slew between the temple and the altar.
They had become the scribes and Pharisees,
affixing themselves to the true house of Israel in 1 Chron. 2:55.
1 Chron. 2:55 And the families of the scribes which dwelt at Jabez; the Tirathites, the Shimeathites, and Suchathites. These are the Kenites that came of Hemath, the father of the house of Rechab.
Do you know what that means?
The sons of Cain made it through the flood!
But, how is that possible?
It is really quite simple and we will learn the exciting truth of the matter when we get to Rev. chapter six.
Let's now return to Genesis chapter four where Cain is being ousted from his native land.
He is concerned that his evil ways might get him killed by the people he encounters.
Genesis 4:15 And the LORD said unto him, Therefore whosoever slayeth Cain, vengeance shall be taken on him sevenfold. And the LORD set a mark upon Cain, lest any finding him should kill him.
Here we see that God is going to protect Cain by placing a mark upon him.
But why should He?
The creep just murdered Abel!
Because Cain will be used to fulfill the "negative part" of God's plan.
You must understand that for every positive there is a
negative: sun/moon, light/dark,
good/bad, Holy Spirit/evil spirit, Christ/Satan, etc., etc.
It seems that for the flesh man, unless he has gone through
he can never truly appreciate the warm sunshine.
But a wise person knows that ultimately the negative becomes
for it, the negative, provides the seedbed for the testing of faith.
What is this "mark" that the LORD set upon Cain?
It is truly amazing to listen and read about the creative
ideas that man is able to imagine
in an attempt to figure out what this "mark" is.
Perhaps it could have been like a "no smoking" sign,
a sharp dagger with a red circle and a slash through the center.
People would recognize this universal symbol and say to
"Look Sam, he has a 'no kill' sign on his forehead,
so we'd better leave him alone.
Darn, I wanted to kill him!"
In Genesis 4:15 God set a sign for Cain.
In other words, He gave him a "pledge" that He would protect him in his journeys.
The word "mark" is the same word
as "token" in Gen. 9:12, 13,
where God gave Noah a sign, a "token" of His covenant
that He would never again flood the earth with water.
It was His pledge.
And He didn't paint a little rainbow on Noah's head, either.
Check it out.
Don't listen to made up stories.
So God "marked", or set aside, Cain to be protected.
Note: You ought to see what preachers and ministers are telling people about the "mark of the Beast" in chapter 13 of the Book of Revelation. They tell them that they are going to have the number "666" tattooed on their foreheads (kind of like the "no smoking" symbol again). And so the ignorance continues from Genesis to Revelation. (You'll either have the truth, "the seal of God", in your forehead (brain) or you'll have deception, "the seal of Satan", which is the "mark of the beast", in your forehead. So don't buy stock in tattoo shops!)
 And Cain went out from the presence of the LORD, and dwelt in the land of Nod, on the east of Eden.
"Sargon the Magnificent" by Mrs. Sidney Bristowe.
In this fascinating history book, Mrs. Bristowe simply
takes the historical works of recognized scholars and substitutes Cain
of Genesis for Sargon of Akkad. She acknowledges that pre-adamites, the
sixth day creation of mankind, were present in Nod, the land of Sumer,
and it was from these peoples that Cain took his wife. If haven't read
it, you're missing out!
Genesis 4:17 And Cain knew his wife; and she conceived, and bare Enoch: and he builded a city, and called the name of the city, after the name of his son, Enoch.
You now know that Cain's wife was not a daughter of Adam and Eve.
And remember, since Cain was not Adam's son,
he is not listed in Adam's genealogy in chapter five.
 And unto Enoch was born Irad: and Irad begat Mehujael: and Mehujael begat Methusael: and Methusael begat Lamech.
But for the sake of brevity, I would have listed them here.
There is, however, one major point of which you should take note.
The names of these kenites are very similar (and some
even the same)
to the names of the offspring of Adam, listed in chapter five.
Methusa-el vs. Methusel-ah
Enoch vs. Enos and Enoch
Mehujael vs. Mahalaeel
Tubal-cain also means producer of weapons. Mrs. Bristowe in her book "Sargon the Magnificent", gives some great history about this worker of brass and iron. And Adah bare Jabal: he was the father of such as dwell in tents, and of such as have cattle.
 And his brother's name was Jubal: he was the father of all such as handle the harp and organ.
 And Zillah, she also bare Tubal-cain, an instructer of every artificer in brass and iron: and the sister of Tubal-cain was Naamah.
And so it was that Cain went forth into the land of Nod and founded Babylon.
The history books declare that about 3800 B.C., "poof",
that great civilization suddenly appeared with such advances in art and law
and astronomy and language, etc.,
that it defies the explanations of evolutionists who require great lengths of time to justify their theories.
It was because of Cain's superior intellect
and the knowledge he had learned from our Father and his earthly parents,
that he was able to easily subdue the sixth day man.
It would be from the religions founded by this one, Cain,
that all the nations of the earth would be made "drunk".
And again regarding Babylon:Rev. 14:8 And there followed another angel, saying, Babylon is fallen, is fallen, that great city, because she made all nations drink of the wine of the wrath of her fornication.
Rev. 17:2 With whom the kings of the earth have committed fornication, and the inhabitants of the earth have been made drunk with the wine of her fornication.
To study the 1st. 11 chapters of Genesis word for word: (live link to) All 11 chapters in one complete study