Thank you for the question on the appearance of Satan to Eve, “In Genesis, why did Satan decide to speak to Eve as a serpent and not as himself or a different creature?”
The Scriptures at times explains the reason why something was going to happen and at times the Scriptures do not give the reason or motivation of what was to happened or what happened. It just records the events.
The question being asked is why did Satan appeared as a serpent and not himself or some other creature is hinted by the interaction between the serpent and Eve. Genesis 3 says this, “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’?” 2 The woman said to the serpent, “We may eat fruit from the trees in the garden, 3 but God did say, ‘You must not eat fruit from the tree that is in the middle of the garden, and you must not touch it, or you will die.’” 4 “You will not certainly die,” the serpent said to the woman. 5 “For God knows that when you eat from it your eyes will be opened, and you will be like God, knowing good and evil” (A searchable online Bible in over 150 versions and 50 languages).
The phrase, “Now the serpent was more crafty than any of the wild animals that the LORD God had made.”, would or may imply his approach to Eve. The comments that I make are speculations since the Scripture doesn’t state the reason why he appeared to Eve in the form of a serpent.
A. If Satan/Lucifer appeared in his angelic form, this may have frightened Eve and caused her to run to Adam who was nearby. The angelic form to contradict the words of God would caused greater suspicion on her part.
B. If Satan/Lucifer appeared in his angelic form, it is most likely that Adam would have also seen him. He would have gone to him and asked what did he wanted to say to them. Adam knew the command of God and may not have accepted Satan’s words.
C. If Satan/Lucifer appeared in some other form as a cow or horse, the appearance of that creature would be obvious to Adam. Certainly, Adam and Eve would have feed or petted the animals. Would Adam walked over to see the animal? Possible as that appearance would be too obvious for Adam not to see him.
D. If Satan/Lucifer appeared as a serpent, then Adam may not see him among the branches as she may be picking some fruits. We don’t know that but it seems that she was near the Tree of Knowledge of Good and Evil. The disguise of being a serpent may have blended his appearance among the branches. Adam may not have seen the serpent speaking to Eve as the conversation was a very short one.
In my conjecture, it is likely that the serpent appeared and or spoke to her before. She may have been familiar with the serpent to some extent since she would see him around where she was picking fruits. Whether he spoke any words to her is unknown. Thus in some manner Eve wasn’t surprise of seeing the serpent on a branch or perhaps speaking to her. The choice of appearing as a serpent was a crafty move by Satan/Lucifer.
SUMMARY: Satan/Lucifer may have taken the form of a serpent so that Adam could not see him and that Eve was picking fruits or stopping in front of branch for some shade. Satan used that moment in time to have that conversation which seem so innocent and non-threatening by the serpent. He was just hanging around the tree!
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