"Cain and Abel represent two classes that will exist in the world till the close of time.
The class of worshipers who follow the example of Cain includes by far the greater portion of the world; for nearly every false religion has been based on the same principle--that man can depend upon his own efforts for salvation.
The history of Cain shows what must be the results. It shows what man will become apart from Christ. Humanity has no power to regenerate itself. It does not tend upward, toward the divine, but downward, toward the satanic.
The holy life of Abel testified against Satan's claim that it is impossible for man to keep God's law."
Patriarchs & Prophets p.72-77 E.G.W.
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.
1 John 3:12
......but what they know naturally,
as brute beasts, in those things they corrupt themselves.
Woe unto them!
for they have gone in the way of Cain,
Jude 1:10,11
By faith
Abel offered unto God a more excellent sacrifice than Cain,
by which he obtained witness that he was righteous,
God testifying of his gifts:
and by it he being dead yet speaketh.
Hebrews 11:4