Satan fell the instant he decided he didn’t need God, that he was sufficient in himself without God, that he was free to displace God and treat himself as if he was God. (Is 14:13) He’s been God’s enemy ever since.
Eve fell similarly, as she preferred being like God to being with God, discerning right and wrong for herself (Ge 3:6), knowing good and evil. (Ge 3:22)
The tragic Fall of Man, bringing ruin and misery upon the entire human race, was a single, simple step away from God, breaking a dietary law, the least of His commandments. (Ja 2:10) What seemed so small a step for man was in fact an infinite leap for all mankind; no willful sin is little.
The Fall continues in us whenever we doubt the goodness of God, or question His justice: we’re essentially presuming we know better than God. Our bitterness, discontent and resentment testify that we’d rather be in charge, that we’d be doing a better job than God in avenging evil and rewarding good. (Ps 119:75)
Similarly, whenever we sin willfully we’re putting our own will first, displacing God’s, putting ourselves in the epicenter of the universe and dishonoring Him. (He 10:26-27)
Put very simply, in every sense that we’re feeling independent of God, that we don’t need Him, that we can do without Him, live apart from Him … as we ignore and neglect Him … this is the pride of life, the very heart of wickedness. (1Jn 2:16)
These are the many shades of pride, self-exaltation exuding from the heart, spilling out continually on every side. The careless, carnal mind, that isn’t continually abiding in thankful, reverent fear, joying in God, and cares not for this, reveals a child of the wicked one, in and through whom the devil freely lives. (Ep 2:2)