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
History will repeat itself in the end...as innocent "Abel" will fall before "Cain" via persecution over the mark of the beast. Remember-Cain wasn't an atheist. He worshipped God his way and Abel worshipped God the way God commanded.
The first conflict recorded in Scripture for us between humans was over worship. And the last conflict between humans recorded for us is over worship.
And the first went, and poured out his vial upon the earth; and there fell a noisome and grievous sore upon the men which had the mark of the beast, and upon them which worshipped his image.
Revelation 16:2