When was the serpent cast out of Eden?
This is a good question for several reasons. The short answer is: "The serpent as was cast out at the same time that Adam and Eve where cast out."
Why? Because the pronouncement by the Lord God was swift and unequivocal:
“The LORD God said to the serpent,
‘Because you have done this,
Cursed are you more than all cattle,
And more than every beast of the field;
On your belly you will go,
And dust you will eat
All the days of your life;’
‘And I will put enmity
Between you and the woman,
And between your seed and her seed;
He shall bruise you on the head,
And you shall bruise him on the heel.’”
This was not some divine "slap on the wrist" as we often suppose. Just what was this pronouncement by God if not the Devil’s condemnation? Is this not as clear a judgment on Satan as we ever read in the Bible? Indeed, it may well be the only instance that we ever read about, although some will insist that symbolic imagery found in the Book of Revelation (12:7-9) is describing yet another judgment. However, a closer examination of Revelation 12 should reveal how the "war in heaven" was, in fact the spiritual battle that took place on earth between Christ and Satan.
I will not take the time to demonstrate that here; suffice it to say Satan's angels were the demons whom Christ faced throughout his ministry. Christ's (Michael's) angels were his disciples (and perhaps certain angelic majesties). We simply cannot ignore the great symbolism found throughout the Book of Revelation; it is bad form to do so. 
There are great treasures in the Bible if we are willing to use our time and effort to look for them. For example, let us consider the following enigmatic passages from Peter’s First Letter, which are believed to convey great significance in this matter:
1 Peter 3:18-20: “For Christ […] having been put to death in the flesh, but made alive in the spirit; in which also He went and made proclamation to the spirits now in prison, who once were disobedient, when the patience of God kept waiting in the days of Noah, during the construction of the ark, …” (emphasis added).
Just what is Peter telling us? Note the subtlety as God relates His Word to us, as if it is specifically intended to “filter out” those who do not have a conscientious desire to learn and be edified. Let us break the passages down by examining each point carefully:
- Christ was put to death in the flesh, but He was then made alive in the spirit.
- What else can this mean but that Christ became the Preincarnate Christ –- Christ in His glorified form. This makes perfect sense because...
- Recall that “Noah walked with God” (Gen. 6:9). That is not hyperbole.
- Christ appeared bodily to many of the Old Testament faithful, just as He did to Noah.
- Having thus been made alive, He went and proclaimed salvation through Noah.
- Noah’s audience was the violent, pre-Flood inhabitants of the Earth.
- These people were disobedient to the Words Christ spoke through Noah as he (Noah) was building the ark for 100 years. This is where “the patience of God kept waiting.”
- Finally, these same pre-Flood inhabitants, all of whom rejected the Message, are now spirits in prison -- at the time Peter wrote his Letter in the first century A.D.
We have unpacked quite a bit here. Should we be surprised that Christ has sovereignty over Time? Why? He is an eternal Being. This is confirmed for us in (at least) the Gospel of John where Jesus told his Jewish audience that Abraham lived to see Him:
John 8:56-58: “‘Your father Abraham rejoiced to see My day, and he saw it and was glad.’ So the Jews said to Him, ‘You are not yet fifty years old, and have You seen Abraham?’ Jesus said to them, ‘Truly, truly, I say to you, before Abraham was born, I am’” (emphasis added).
Are we to reject this declaration by Christ that Abraham visibly saw Him? Note that Christ may just as easily have said: “Noah rejoiced to see My day.” We know that Noah was a “preacher of righteousness” (Gen. 6:9, 2 Peter 2:5). He ministered to those alive while he built the ark, but everyone other than his immediate family rejected the Message. Therefore, the violent, pre-Flood inhabitants to whom Noah once preached are described by Peter as “spirits now in prison.”
All of those wicked people had been long gone, their spirits now languishing in the flames of Hades (Lk. 16:19ff, cf. 2 Peter 2:4, Tartarus). Recall that in the first chapter of Peter’s Letter we are told:
1 Peter 1:11: “[The] Spirit of Christ [dwelled] within [the Old Testament prophets]” as they “prophesied of the grace that would come” to those who were willing to obey."
From this, it seems plausible that Christ not only operated through Noah: He also ministered “in the Spirit” through all the O/T prophets. That is simply a direct observation of the text. Let us not miss a significant point here. It might be helpful to remember, as before, that “Noah walked with God” (Gen. 6:9). Christ existed as God in the Spirit and manifested Himself as a physical being visibly and often. And, this makes perfect sense. That is because it is Christ Who:
- Created the world (Col. 1:16-17, Eph. 3:9, 1 Cor. 8:6);
- Is the image of the invisible God (Col. 1:15, 2 Cor. 4:4);
- Is the LORD Who “spoke to Moses face to face, just as a man speaks to his friend” (Ex. 33:11), and
- Is the sole mediator between heaven and Earth (1 Tim. 2:5, Heb. 8:6, 9:15).
All of these facts would indicate that it is through Christ that people have a direct connection to God the Father. In Paul’s First Letter to Timothy, the apostle tells us:
1 Timothy 2:5: “For there is one God, and one mediator also between God and men, the man Christ Jesus...”
It should be relatively clear to those who have studied the subject that a personal encounter with the Preincarnate Christ did not necessitate death. And, this is how we may understand that human beings could stand face-to-face with God (Ex. 33:11), and did so many times without loss of life.
Now, if these things are true, should we be surprised to learn that Christ traveled back even further to the Garden of Eden? And why would He do that? To pronounce judgment on the serpent! But this could not be accomplished until He had offered Himself as the Sacrifice for all humanity. Adam and Eve stood just as guilty as the serpent in the Garden.
Christ would now possess full authority to directly condemn Satan for his actions. It appears to be the case that the passages from 1 Peter 3:19-20 as well as 1 Peter 1:11 reveal a glimpse of much greater truths if we are willing to pursue them. Christ, as God, is an eternal being, capable of stepping into and out of Time at will. Why is this a surprise to so many? (cf. Ex. 33:11).
We should remember that Christ proclaimed to his disciples:
John 12:31: “Now judgment is upon this world; now the ruler of this world will be cast out.”
Obviously, “the ruler of this world” would be cast out after Christ’s Sacrifice, and, I suggest that would be the curse in the Garden, where Satan would then spend all his days eating dust (on the earth). Let us contrast this with a statement by Christ from the Gospel of Luke:
Luke 10:18: “And [Christ] said to [the seventy disciples], ‘I was watching Satan fall from heaven like lightning.’”
In both of these cases it appears that Jesus envisions the certainty of the Devil’s judgment as a near-future occurrence to Him, something which we have great difficulty comprehending as finite beings that exist in a world of finite time. At what other point would Satan, in the form of a serpent, receive a divine sentence if not right here, moments after he had so obviously lied and perpetrated spiritual murder against the first couple – with ramifications that would span all of human history?
In these two passages, the Lord GOD has just prophesied the fate of the serpent: “He [Jesus] shall bruise you on the head.” Indeed, if this extrapolation of 1 Peter 3:18-20 is correct, Jesus of Nazareth had just been “[bruised] on the heel” through crucifixion, where both his feet were nailed to a wooden cross. He would desperately have tried to lift his terribly mutilated body on those bruised, pierced heels to prevent suffocation.
Christ, now a Spirit Being, would surely waste no time pronouncing a sentence on this great enemy; Genesis 3:14-15 appears to describe that sentence. Ultimately, of course, the Devil’s fate would be the Lake of Fire. As a spiritual being, he has no possible hope of salvation (Matt. 25:41).
We should not overlook the fact that the meaning of these verses is that the Devil has likely just been “cast out” -- metaphorically, he has “fallen from heaven like lightning” (Lk. 10:18). Here, perhaps we are to understand that “[eating] dust all the days of your life” (Gen. 3:14) is also emblematic of Satan’s confinement, consisting merely of “roaming about on the Earth and walking around on it” (cf. Job 1:6-7, 2:1-2). What is the Earth if not dirt and dust?
As mortal beings, it’s unlikely that we can plumb the depths of the spiritual consequences imposed on Satan at that moment.
I propose that, Yes, Satan was cast from the Garden immediately just as with the first couple.
 Daniel’s people were the Israelites, those protected by Michael (Dan. 10:13, esp. Dan. 10:21, 12:1). It was Christ Who was the rock that followed and protected them in the wilderness (1 Cor. 10:4). Further, Michael was the one to dispute with the Devil over the body of Moses (Zechariah 3) represented by the Old Covenant relationship (Law and the Prophets), just as the body of Christ is represented by the New Covenant.
 God is omnipotent. It is, therefore, impossible for a war to “break out” in the holiest of the heavens because nothing can occur against the will of a Being with absolute power. This also means that angels, who exist in His magnificence could simply never fall, never rebel, because to exist in the paradise of God is to share His mighty intellect. How could anyone reject such thoughts or disagree with Him? If we are disposed to believe that some angels fell, we are then going to need significant evidence to prove how that could possibly occur.