GENESIS 3:5
 

[NKJV]

For God knows that in the day you eat of it your eyes will be opened, and you will be like God, knowing good and evil.”
 

[FBV]

“It's because God knows that as soon as you eat it, you'll see things differently, and you'll be like God, knowing both what is good and what is evil.”

See the vanities in the devil's temptations, for his temptations are like his meaningless journeys: going to and fro, and going up and down. Satan goes to and fro, up and down, because Satan follows Satan's temptations. That means any one who follows Satan's temptations would also be going to and fro, up and down, in vain and meaningless wanderings. At the end of it all, there's nothing new such one would say he/she had done that had not been done before, except for the useless wasting of more lives, time and resources. Why would you follow the temptations or counseling of the devil who obviously has not led himself and his demons well. Satan's own heart and mind are parts of the curses plaguing Satan since iniquity was found in him.
 

According to the serpent, eating of the tree of knowledge of good and evil would open one's eyes to be like God in knowing the good and evil that God already knows. The serpent admits that God knows good and evil, but refused to accept what the God that knows good and evil calls evil or forbids for mankind created in God's image after God's Likeness. God was already doing for the woman what the serpent was promising her as reward from eating the forbidden tree. God was the Eyes for mankind to see through and to know the nature of everything, but the devil just wanted mankind to remove their dependence, reliance or trust on God into depending or trusting themselves.
 

When the God who knew all things called that forbidden act, "evil" or deadly, the serpent protested and deceived the woman into committing the act to have an open eyes that know what is good and evil like God already knew.
 

• ▪If God's Open Eyes that knows good and evil tell mankind what is good and evil, the serpent would deceive the woman to reject what God revealed as good, evil, life or death. But,
   
• ▪If mankind's Open eyes would know good and evil tell mankind what is good and evil, the serpent would accept that as being wise, civilization, freedom and illumination, for mankind. 
   

This is called, "Being wise in your own eyes" or "Being wise in your own conceit" and it's basically rejecting God's Wisdom and God's leadership instead for man's self leadership that depends on man's eyes or his ability to know good and evil. We have seen where being wise in his own eyes have led the serpent to, and though he was more crafty than all the beast of the ground the serpent became cursed above all the beast of the ground.
 

Berean Study Bible (BSB)

[Isaiah 5:21] — "Woe to those who are wise in their own eyes and clever in their own sight."
 

We must walk by faith in God, not by sight or wiseness in our own eyes.
 

Do not be wise in your own eyes; fear the LORD and turn away from evil. This will bring healing to your body and refreshment to your bones. [Proverbs 3:7-8]