God created the tree of the knowledge of good and evil and told Adam that if he ate of the tree he would surely die.
Genesis 2:9 and 17
9 And out of the ground made the LORD God to grow every tree that is pleasant to the sight, and good for food; the tree of life also in the midst of the garden, and the tree of knowledge of good and evil.
17 But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die.
Then when I read:
Gen 3:1 KJV
Now the serpent was more subtil than any beast of the field which the LORD God had made.
And he said unto the woman, Yea, hath God said, Ye shall not eat of every tree of the garden?
Several people have told me that the Serpent was actually Satan in disguise, but I find no scripture to back up that assertion.
Whether or not that is true actually doesn't matter since Satan is evil.
Since the Serpent beguiled Eve, would that mean that evil was already present or not?
Although I cannot give you a definitive answer to your question, I will tell you what I have come to believe from my study of the Bible.
It may have been God himself who decided to use the image of a dove in this case.
At that time the heart of worship was the Pentateuch, or the first five books of the Bible written by Moses. these were supported by the prophets.
All Israelite children were educated on these books, since the Law was the guide for all facets of life.
They would be very familiar with the story of Noah and the flood, and when Noah sent out Raven to see if the waters had begun to dry up the Raven did not return, so Noah then sent out a Dove which returned with an olive branch.
Gen 8:7 through 11
7 And he sent forth a raven, which went forth to and fro, until the waters were dried up from off the earth.
8 Also he sent forth a dove from him, to see if the waters were abated from off the face of the ground;
9 But the dove found no rest for the sole of her foot, and she returned unto him into the ark, for the waters were on the face of the whole earth: then he put forth his hand, and took her, and pulled her in unto him into the ark.
10 And he stayed yet other seven days; and again he sent forth the dove out of the ark;
11 And the dove came in to him in the evening; and, lo, in her mouth was an olive leaf pluckt off: so Noah knew that the waters were abated from off the earth.
And just as the Dove announced that the world was beginning to become available as a habitant. So the Dove in:
Matthew 3:16 KJV
And Jesus, when he was baptized, went up straightway out of the water: and, lo, the heavens were opened unto him, and he saw the Spirit of God descending like a dove, and lighting upon him:
Mark 1:10 KJV
And straightway coming up out of the water, he saw the heavens opened, and the Spirit like a dove descending upon him:
Luke 3:22 KJV
And the Holy Ghost descended in a bodily shape like a dove upon him, and a voice came from heaven, which said, Thou art my beloved Son; in thee I am well pleased.
John 1:32 KJV
And John bare record, saying, I saw the Spirit descending from heaven like a dove, and it abode upon him.
Announced that Heaven was beginning to become to become available as an eternal habitant for man.
Of course that is only my belief and you may or may not accept that.
"you can vote however you want"