There is general agreement that Satan had already rebelled when Eden was created and that Eve sinned just a few hours/days after creation. Are there any hypotheses about how satan got into Eden immediately after its creation? It's rather unbelievable that he was admitted there after he had been banned from Heaven. Secondary questions with no answers are: how could he take the shape of a serpent, speak Eve's language, convince her etc.
First, understand that Satan was, and still is, the god of this world:
Now is the judgment of this world: now shall the prince of this world be cast out. — John 12:31
In whom the god of this world hath blinded the minds of them which believe not, … — 2Cor 4:4
Then notice carefully what happened when Satan offered some of his power over the world to Jesus:
And the devil, taking him up into an high mountain, shewed unto him all the kingdoms of the world in a moment of time. And the devil said unto him, All this power will I give thee, and the glory of them: for that is delivered unto me; and to whomsoever I will I give it. If thou therefore wilt worship me, all shall be thine. And Jesus answered and said unto him, Get thee behind me, Satan: for it is written, Thou shalt worship the Lord thy God, and him only shalt thou serve. — Luke 4:3–8
Jesus rebuked Satan for tempting him, but he didn't in any way deny Satan's claim of being able deliver this power.
God did choose a group of people (Judaism, physical Israel) to set an example to the world of what would happen if they followed God's rules according to their literal meaning, and not those of Satan's world. And he did later establish a group of people (Christianity, spiritual Israel) to set an example to the world of what would happen if they followed God's rules according to their spiritual meaning. But in general it's obvious (e.g. read today's news) that it is not God that is running this world (yet).
So, to answer the original question, Satan was there because he was, and still is, in charge of the Earth.
It was part of God's eternal plan that the Devil should enter into Eden and tempt Adam and Eve. Without this no other part of God's plan of redemption could have taken place.
The fall of Satan may have been just a few moments, even seconds, before he deceived Eve. Or even Satan fell in the same instant he tempted Eve.
It appears that the first time the word we translate into English as "Satan" didn't appear in the Hebrew scriptures until Job 1:6 which speaks of this one appearing in heaven along with the angels. This was during the initially prosperous lifetime of Job, when Satan sought clearance to tempt Job, whom he accused of only serving God for gain. It is significant that the word means, "The Accuser".
Also, 1 Chronicles 21:1 has another very early use of this word. This was in the time of King David, when Satan tempted David to take an illegal census. However, the word Satan never appears in the Bible until after the Flood. It certainly never appears as an identification of anyone either in Eden, or in the garden that was in the east of Eden.
There will be a reason for that, but the answer I give is that although Satan is never said to be there, the serpent is. The qualities of serpentine cunning and subtlety are the point of speaking of a creature that would naturally be in that place, as were all the other animals and birds.
The Bible stated that God had brought all the animals to Adam, for him to name, prior to the encounter the woman had with the serpent. That is how a serpent's appearance in the garden would give no cause for suspicion. As for it speaking, well, that's another question!
We are simply told in breathtakingly minimalistic wording what happened, not how it happened. The only other thing we are told about this serpent in the garden is that it was consigned to crawl on its belly and to eat [lick] dust. Apparently there are vestigial legs in the skeletons of serpents, according to the experts.
Of note is that the words Satan and Devil are not actually names, but descriptions of qualities. In the last book of the Bible we see the clear link between the serpent in Eden, Satan, the Devil, and the great red Dragon that was hurled out of heaven:
"And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world. He was cast out into the earth, and his angels were cast out with him. And I heard a loud voice saying in heaven, Now is come salvation and strength, and the kingdom of our God, and the power of his Christ; for the accuser of our brethren is cast down, which accused them before our God day and night." Revelation 12:9-10
That is as much as we are told (regarding your question) but from the first mention of the two trees, the account starts using symbolism. The tree of life and the tree of the knowledge of good and evil are not literal trees. Eating literal fruit from the latter could never convey any knowledge. Likewise, the appearing of the serpent on that tree continues the symbolism. Satan is invisible, but he uses agencies to deceive and to bring darkness and sin. That symbolic tree never gets another mention in scripture, yet the thing it symbolises is a recurring theme in scripture. The symbolism regarding Satan in the garden does not require an answer as to "how he got in", but as to what his entrance results in, for those who listen to the agencies he uses. They will become exposed as spiritually naked and feel shame - Rev. 3:17-18.
("There is general agreement that Satan had already rebelled when Eden was created and that Eve sinned just a few hours/days after creation."..)
Your assumption will negate potential answers to your primary question.
Let me switch to one of your secondary questions. ("how could he take the shape of a serpent, speak Eve's language, convince her etc.")
- Satan is not a proper name. It can be used as a description, role, function or title. Here is a similar, but modern day example:
The Speaker of the United States House of Representatives. In this usage, Speaker, is all four meanings, but is not a proper name. Satan likewise, is all four, yet not a proper name.
- Satan is not a talking snake. Serpent, along with Dragon, are Anglicized astrological names. We call them constellations. Genesis referred to them as signs, and Job references the word Mazzoroth. Both signs described the same person through oral stories, and stars.
The image of a talking snake dangling from a tree is not from scripture, it's from cartoon art. A better concept of Satan (I believe proper English requires, the, be placed before Satan) can be found in Job. He is seen in all four meanings of the word, satan. And, talking is what he is supposed to do, as the Satan.
"There is general agreement that Satan had already rebelled when Eden was created and that Eve sinned just a few hours/days after creation."
Before Eve was created, Adam had been given the assignment to name all land animals and birds (Genesis 2:19-20). We do not know how much time he spent in analysing each species before naming it, but even with just a few days per species, he could have been decades old by the time Eve was created. Based on that, and that Adam was 130 years old when his 3rd son Seth was born (Genesis 5:3), technically Adam could have been for example 90 years old and Eve 40 years old at the time they sinned.
But those numbers are just an example. The Bible does not provide us sufficient data to state their ages at that time with any certainty. Nevertheless there is also no Biblical basis for that Eve sinned just a few hours/days after creation.
Also the Bible does not state that Satan was banned from heaven immediately or even soon after his rebellion. For example Jude verse 9 describes a disagreement between Satan and Michael the archangel that apparently happened thousands of years after the rebellion in Eden (being in reference to Moses' body). Likewise, nothing stopped Satan from trying to tempt Jesus much later in Luke 4:5-7 where it states:
5 So he brought him up and showed him all the kingdoms of the inhabited earth in an instant of time. 6 Then the Devil said to him: “I will give you all this authority and their glory, because it has been handed over to me, and I give it to whomever I wish. 7 If you, therefore, do an act of worship before me, it will all be yours.”
The two secondary questions about how could he take the shape of a serpent or speak Eve's language could also be asked regarding the angel that spoke through the donkey that Balaam was riding (Numbers 22:26-31). Spirit creatures, being invisible, can make it appear as if a sound comes through something that does not normally speak. For that reason he did not necessarily have to take the shape of a snake.
As to convincing Eve, the situation was more like a case where a person is tempted to join a heist with the promise of a large reward. The person may know that it is morally wrong to steal but is tempted by a desire to gain something from the theft. The Bible says that Eve was "deceived" (1 Timothy 2:14) and it was due to her believing the lie spoken by the "snake".
How did Satan get into Eden?
Now the serpent was more crafty than any of the wild animals the Lord God had made. He said to the woman, “Did God really say, ‘You must not eat from any tree in the garden’?” - Genesis 3:1
God permitted the Devil (Satan) to somehow get into the Garden of Eden in order to tempt Eve into sinning. This was foreseen in God’s Divine plan for humanity. With Adam’s fall we received a great Redeemer in Our Lord, Jesus Christ.
Satan being metaphorically described as a serpent almost implied that he somehow slipped in unseen or if you wish slithered in!
We can recall that God allowed Satan to put Job to the test!
6 Now there was a day when the sons of God came to present themselves before the Lord, and Satan[a] also came among them. 7 The Lord said to Satan, “From where have you come?” Satan answered the Lord and said, “From going to and fro on the earth, and from walking up and down on it.” 8 And the Lord said to Satan, “Have you considered my servant Job, that there is none like him on the earth, a blameless and upright man, who fears God and turns away from evil?” 9 Then Satan answered the Lord and said, “Does Job fear God for no reason? 10 Have you not put a hedge around him and his house and all that he has, on every side? You have blessed the work of his hands, and his possessions have increased in the land. 11 But stretch out your hand and touch all that he has, and he will curse you to your face.” 12 And the Lord said to Satan, “Behold, all that he has is in your hand. Only against him do not stretch out your hand.” So Satan went out from the presence of the Lord. -Job 1:6-12
Satan being an angel had angelic powers and as such learning Eve’s language posed no hardship for the fallen angel.
St. John in his Apocalypse calls the Ancient Serpent, Satan!
7 Then war broke out in heaven. Michael and his angels fought against the dragon, and the dragon and his angels fought back. 8 But he was not strong enough, and they lost their place in heaven. 9 The great dragon was hurled down—that ancient serpent called the devil, or Satan, who leads the whole world astray. He was hurled to the earth, and his angels with him. - Revelation 12-7-8
The first creation story is prophetic of the new heavens and new earth. It starts out with a description of the current state of the earth 'becoming' a void with darkness covering the Abyss. If you haven’t noticed, God said “Let there be Light” four days before the sun and moon were created. The man and woman are Jesus and his bride. Eve is the bride of the Shining One, Satan.
the earth was a formless wasteland, and darkness covered the abyss (Gen 1:2 NABO)
Then God said, "Let there be light," and there was light…. Thus evening came, and morning followed-- the first day. (Gen 1:3-5 NABO)
God made the two great lights, the greater one to govern the day, and the lesser one to govern the night; and he made the stars… Evening came, and morning followed-- the fourth day. (Gen 1:16-19 NABO)
Satan is the cornerstone of Christ's work of salvation, which he began as the first Adam. Adam's sin is prophetic of him laying down his life in a sacrifice for sin. The flashing sword is sharpened for the day of wrath, the wrath of the Lamb, and is the sacrifice of being 'made to be sin' on the day of the great slaughter. I couldn’t find a verse that clearly says Jesus is the cornerstone.
in his name this man stands before you healed. He is 'the stone rejected by you, the builders, which has become the cornerstone (Act 4:10-11 NABO)
I will sharpen my flashing sword, and my hand shall lay hold of my quiver. "With vengeance I will repay my foes and requite those who hate me. (Deu 32:41 NABO)
I have come to set the earth on fire, and how I wish it were already blazing! (Luk 12:49 NABO) For by my wrath a fire is enkindled that shall rage to the depths of the Abyss, Consuming the earth with its yield, and licking with flames the roots of the mountains. (Deu 32:22 NABO) Down I went to the roots of the mountains; the bars of the Abyss were closing behind me forever (Jon 2:7 NABO)
The vision of the evenings and the mornings is true, as spoken (Dan 8:26 NABO) In the morning you will say, 'Would that it were evening!' and in the evening you will say, 'Would that it were morning!' for the dread that your heart must feel and the sight that your eyes must see. (Deu 28:67 NABO) morning after morning it shall pass, By day and by night; terror alone shall convey the message. (Isa 28:19 NABO)
Then will the LORD create, over the whole site of Mount Zion and over her place of assembly, A smoking cloud by day and a light of flaming fire by night. (Isa 4:5 NABO)
A thief comes only to steal and slaughter and destroy; I came so that they might have life and have it more abundantly. (Joh 10:10 NAB)
But the day of the Lord will come as a thief in the night; in the which the heavens shall pass away with a great noise (2Pe 3:10 KJV)
all the people shall shout aloud. The wall of the city will collapse, and they will be able to make a frontal attack." (Jos 6:5 NABO)
Master of the Demon Sin, therefore will he lift up his head.
If you do well, you can hold up your head; but if not, sin is a demon lurking at the door: his urge is toward you, yet you can be his master." (Gen 4:7 NABO) robed in splendor (he) judges nations, crushes heads across the wide earth, Who drinks from the brook by the wayside and thus holds high the head (Psa 110:6-7 NABO)
Is God unjust, humanly speaking, to inflict his wrath? Of course not! For how else is God to judge the world? (Rom 3:5-6 NABO)
And why not say-- as we are accused and as some claim we say-- that we should do evil that good may come of it? (Rom 3:8 NABO)
He is the temple with not one stone left standing upon another, the abomination of desolation is set up in him. There will be wars and rumors of wars, but this Day of the Lord is followed by the second coming as the Way of the Lord in the desert. The Crucifixion is prophetic of the first coming as the sacrifice and the second coming as the resurrection, within the same generation. Apparently, the worm attacked the sapling also.
But he was speaking about the temple of his body. (Joh 2:21 NABO)
There shall not be left here one stone upon another… Tell us, when shall these things be? and what shall be the sign of thy coming, and of the end of the world? (Mat 24:1 KJV)
it is appointed that human beings die once, and after this the judgment, so also Christ… will appear a second time (Heb 9:27-28 NABO)
But I am a worm, not a man, scorned by men, despised by the people. (Psa 22:7 NAB)
God sent a worm which attacked the plant, so that it withered (Jon 4:7 NABO)
He grew up like a sapling before him, like a shoot from the parched earth (Isa 53:2 NABO)
Jacob/ Israel is born ‘striking’ at the heal of Esau, the first born. It is a repeat of Satan striking at the heel of Adam, the Messiah. Noah gets treads the winepress, gets drunk, and is found to be naked, like Adam. Adam and Noah start out in a barren land. Israel has the sky like iron and the ground like bronze. The king of Babylon, the ruler of this world, is fettered in iron and bronze. Satan is the ruler of this world. The world is Babylon. The promise is Israel. All are strangers and foreigners on earth.
The sky over your heads will be like bronze and the earth under your feet like iron. (Deu 28:23 NABO)
But leave in the earth its stump and roots, fettered with iron and bronze (Dan 4:12 NABO)
As with a terebinth or an oak whose trunk remains when its leaves have fallen. (Holy offspring is the trunk.) (Isa 6:13 NABO)
saw it and greeted it from afar and acknowledged themselves to be strangers and aliens on earth…Therefore, God is not ashamed to be called their God, for he has prepared a city for them. (Heb 11:13-16 NABO)
Esau's blessing is far from the fertile earth, far from the dew of the heavens. Christ's kingdom is not of this world. The king of Babylon will take his seat on the mount of assembly, far above the stars of God. Jesus ascends far above the heavens themselves. Esau, the first born, like Jesus, the first born. Esau will throw off the yoke of his brother. Jesus’ yoke is easy and his burden light. Christ’s story starts with Adam and continues as Esau.
far from the fertile earth shall be your dwelling; far from the dew of the heavens above (Gen 27:39 NABO)
I will scale the heavens; Above the stars of God I will set up my throne; I will take my seat on the Mount of Assembly, in the recesses of the North (Isa 14:13 NABO)
The one who descended (Jesus) is also the one who ascended far above all the heavens, that he might fill all things. (Eph 4:10 NABO)
when you become (ruler), you shall throw off (Jacob’s) yoke from your neck." (Gen 27:40 NABO)
my yoke is easy, and my burden light." (Mat 11:30 NABO)
Where I am going you cannot come." (Joh 8:21 NABO)
Jacob's ladder is better viewed as dirt heaped up for a ramp or** highway in the desert**. Make straight in the desert, a highway for the Lord on the day of his resurrection from his sacrifice. The same story. One for Satan/ Jacob/ David/ king of Babylon with the promise of Israel and one for Christ. Similar to Jesus having the benefits assured to David.
corresponding verb, salal, means "to heap up" something, such as dirt for a highway or ramp.
In the desert prepare the way of the LORD! Make straight in the wasteland a highway for our God! (Isa 40:3 NABO)
And that he raised him from the dead never to return to corruption he declared in this way, 'I shall give you the benefits assured to David.' (Act 13:34 NABO)
The Ancient Serpent of Old becomes much greater than before, as the Ancient One of Days taking his seat upon a throne set up on the mount of assembly. This is David, the Morning Star, subjecting himself and his kingdom to Jesus, your God, the Son of Man. Peter is the rock upon which Jesus will build his church. Israel will be a nation of priest. Jesus calls Peter Satan. Peter is the cornerstone apostle of the new Jerusalem.
Is not my house firm before God? He has made an eternal covenant with me, set forth in detail and secured. Will he not bring to fruition all my salvation and my every desire? (2Sa 23:5 NABO)
David, the bright morning star (Rev 22:16 NABO)
I was restored to my kingdom, and became much greater than before. (Dan 4:33 NABO)
You, O king, are the king of kings; to you the God of heaven has given… making you ruler over them all (Dan 2:37-38 NABO)
He turned and said to Peter, "Get behind me, Satan! (Mat 16:23 NABO)
And so I say to you, you are Peter, and upon this rock I will build my church, and the gates of the netherworld shall not prevail against it (Mat 16:18 NABO)
He took me in spirit to a great, high mountain and showed me the holy city Jerusalem coming down out of heaven from God… The wall of the city had twelve courses of stones as its foundation, on which were inscribed the twelve names of the twelve apostles of the Lamb. (Rev 21:10-14 NABO)
they shall serve the LORD, their God, and David, their king, whom I will raise up for them (Jer 30:9 NABO)
You shall be to me a kingdom of priests, a holy nation. That is what you must tell the Israelites." (Exo 19:6 NABO)
And, finally, if you think I am preaching something other than Christ raised from the dead, it seems to be expected:
But even if we or an angel from heaven should preach (to you) a gospel other than the one that we preached to you, let that one be accursed! As we have said before, and now I say again, if anyone preaches to you a gospel other than the one that you received, let that one be accursed! (Gal 1:8-9 NABO)
Christ ransomed us from the curse of the law by becoming a curse for us (Gal 3:13 NABO)