Who's to say Satan wasn't Jesus' human side?
Jesus even went so far as to put Himself on the pinnacle.
4 Then was Jesus led up of the Spirit into the wilderness to be tempted of the devil.
Mt 4.
Scripture says so. Again, everything in the NT is against such an idea.
Little "d." It's not inconceivable that the humanity of Jesus Christ had to be subdued.
How can adjectives be entities?
What’s an adjective? Satan is a noun and devil is both a noun and an adjective.
Mar 3:22 And the scribes who came down from Jerusalem were saying, “He is possessed by Beelzebul,” and “
by the prince of demons he casts out the demons.”
Mar 3:23 And he called them to him and said to them in parables, “
How can Satan cast out Satan?
Mar 3:24 If a kingdom is divided against itself, that kingdom cannot stand.
Mar 3:25 And if a house is divided against itself, that house will not be able to stand.
Mar 3:26 And if Satan has risen up against himself and is divided, he cannot stand, but is coming to an end.
Luk 10:17 The seventy-two returned with joy, saying, “Lord, even the demons are subject to us in your name!”
Luk 10:18 And he said to them, “
I saw Satan fall like lightning from heaven.
Luk 13:10 Now he was teaching in one of the synagogues on the Sabbath.
Luk 13:11 And behold, there was a woman who had had
a disabling spirit for eighteen years. She was bent over and could not fully straighten herself.
Luk 13:12 When Jesus saw her, he called her over and said to her, “Woman, you are freed from your disability.”
Luk 13:13 And he laid his hands on her, and immediately she was made straight, and she glorified God.
...
Luk 13:16 And ought not this woman, a daughter of Abraham
whom Satan bound for eighteen years, be loosed from this bond on the Sabbath day?”
Luk 22:3 Then Satan entered into Judas called Iscariot, who was of the number of the twelve.
2Co 2:11 so that we would not be outwitted by Satan; for we are not ignorant of his designs.
2Co 11:14 And no wonder, for even Satan disguises himself as an angel of light.
2Co 11:15 So it is no surprise if his servants, also, disguise themselves as servants of righteousness. Their end will correspond to their deeds.
Rev 12:7 Now war arose in heaven, Michael and his angels fighting against the dragon. And the dragon and his angels fought back,
Rev 12:8 but he was defeated, and there was no longer any place for them in heaven.
Rev 12:9 And the great dragon was thrown down, that ancient serpent, who is called the devil and Satan, the deceiver of the whole world—he was thrown down to the earth, and his angels were thrown down with him.
Rev 20:2 And he seized the dragon, that ancient serpent, who is the devil and Satan, and bound him for a thousand years,
(All ESV.)
All 36 times that Satan is used in the NT, it is used as a noun. The verses above clearly show that Satan refers to a specific spiritual being who is in opposition to God--the one who is also called the devil and "that ancient serpent"--as it does in every NT verse and many OT verses.