what have you read that incites the above quote from your op?
the NT reveals that Lucicfer, the devil was thrown out of heaven and 1/3rd of the angels with him after he lost his bid for the throne of God in his rebellion for the ruler of heaven
18So He said to them, “I saw Satan fall like lightning from heaven Luke 10:18
In Luke 10:18 Jesus says, “I saw Satan fall like lightning from heaven.” The context of these words is the return of the
70 (or 72) disciples that Jesus had sent out to evangelize and prepare His way to Jerusalem (see verse 1). When the 70 return and give their report, they are joyful and a little surprised that “even the demons submit to us in your name” (verse 17). Jesus’ first words in reply are, “I saw Satan fall like lightning from heaven” (verse 18).
In referencing Satan’s fall from heaven, Jesus most likely had in mind Isaiah 14:12, “How you have fallen from heaven, morning star, son of the dawn! You have been cast down to the earth, you who once laid low the nations!” The fall of Satan that Jesus saw happened after Lucifer’s sin, before Adam and Eve’s temptation in the Garden of Eden. In his pride, Lucifer had lifted himself up, but God had cast him down out of his original place in heaven (although he retains a
limited access to heaven for now, according to Job 1:6). Jesus’ statement in Luke 10:18 speaks of Jesus’ pre-existence and the Lord’s defeat over the power of Satan in a general sense.
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so you are right when you state that God did not create the devil. the devil was originally an angel and he determined to take God's place and he failed
ignorance is the lack of knowledge by any individual who seeks to understand something
when we find the knowledge concerning the thing we wish to understand, we can say we are no longer ignorant
sin creates separation between us and God, just like the sin of rebellion in heaven from Lucifer created separation from who he was to what he became...angel to the devil
ignorance is one thing, which can be fixed
disobedience is another. Adam and Eve disobeyed God = sin = separation