Perspective

After the fall, I can imagine one of the first things that Adam and Eve noticed was how extremely impaired their perspective was.
Before they sinned, Adam and Eve were completely cared for by God, and therefore had nothing to be afraid of or worry about. God and His Creation was their entire world, so their eyes were always focused on Him. He was truly their All in All.
After they sinned, however, their vision moved away from the spiritual. It was pulled down to earth and their physical selves, "Then the eyes of both of them were opened and they realized they were naked..." Gen 3:7.

Perspective is a strong weapon of Satan's. Because we have sin, the way we view God and the spiritual realm can never be fully mended in this life. At one time we could see, but now its almost like we have to re-access it all by re-identifying it as we try to distinguish good from evil. I know at least for myself, my biggest battle is keeping hold of the insights God gives me into His mind and the spiritual realm and not allowing Satan to deceive me into despairing, losing faith, calling good things evil, or other such effects that come from him slipping his own perspective over God's.

The Devil is shrewd, and he will try to deliver the perspective from a source that we trust, such as the church. He will try and make us believe that something has always been a certain way, when really it is an error of this day and age.

We have to rely on scripture entirely so that the curtain can't be lowered, and so we can have firm faith in the truth that God has already made his enemies his footstool.