Thou art the anointed cherub that covereth; and I have set thee so.... Thou wast perfect in thy ways from the day that thou wast created, till iniquity was found in thee. Ezekiel 28:14, 15.
It is impossible to explain the origin of sin so as to give a reason for its existence. Yet enough may be understood concerning both the origin and the final disposition of sin, to make fully manifest the justice and benevolence of God in all His dealings with evil. Nothing is more plainly taught in Scripture than that God was in no wise responsible for the entrance of sin.... Sin is an intruder, for whose presence no reason can be given. It is mysterious, unaccountable; to excuse it, is to defend it. Could excuse for it be found, or cause be shown for its existence, it would cease to be sin. Our only definition of sin is that given in the word of God; it is “the transgression of the law;” (1 John 3:4) it is the outworking of a principle at war with the great law of love which is the foundation of the divine government.19The Great Controversy, 492, 493.
Sin originated in self-seeking. Lucifer, the covering cherub, desired to be first in heaven. He sought to gain control of heavenly beings, to draw them away from their Creator, and to win their homage to himself.... Thus he deceived angels. Thus he deceived men. He led them to doubt the word of God, and to distrust His goodness.... Thus he drew men to join him in rebellion against God, and the night of woe settled down upon the world.20The Desire of Ages, 21, 22.
Sin appeared in a perfect universe.... The reason of its inception or development was never explained and never can be, even at the last great day when the judgment shall sit and the books be opened.... At that day it will be evident to all that there is not, and never was, any cause for sin. At the final condemnation of Satan and his angels and of all men who have finally identified themselves with him as transgressors of God's law, every mouth will be stopped. When the hosts of rebellion, from the first great rebel to the last transgressor, are asked why they have broken the law of God, they will be speechless. There will be no answer to give.21The Signs of the Times, April 28, 1890.
From That I May Know Him - Page 15